Their role in the Middle East and North Africa was pretty similar to that of the French and British, who succeeded them. The French and British rule of their areas is generally called colonial rule, the Ottoman rule isn't. Why so?
Colonialism in its strict and historic sense means the practice of settling a large number of colonists in subject countries, as did the British in North America, Ireland, Southern Africa, Australia, New Zeeland, the French in Algeria, the Spanish and Portuguese in Latin America, the Russians in virtually all of their annexed territories, and many parallel examples in the pre-modern world. In this strict sense the Ottoman Turks did not practice colonialism; they did not send significant numbers of Turks to live in conquered lands. The Ottoman Empire was, however, an imperial power which ruled a large number of foreign countries against the will of the native population
The Ottoman Empire, like China, did not fit the "classic" definition of colonial power.
The European countries are considered "colonists" because they colonized or settled lands far from their homelands in the Americas, Africa, Asia, and Australia.
The Ottomans (and Chinese) conquered areas that were outside of, but adjacent to, their homelands. I would call it a "creeping" colonization. But many people characterize these two countries as "conquerers," rather than "colonizers."
The French and British rule of their areas is generally called colonial rule, the Ottoman rule isn't.
Actually, that's not quite right. You can see the Ottomans listed here at the side of other "well known" colonial powers like the US or Japan. The Ottomans were active in the Balkans, North Africa, and the Arab World.
I think it's worth briefly describing what other European colonialism looked like to put the Ottoman colonialism in context.
What one often means by colonialism is countries sending waves of settlers overseas, as occurred when the major colonial powers (Spain, Portugal, France, and the UK) colonized the Americas. State sponsored migrations like those slowed down after former American colonies gained their independence. There were a handful of major settlements outside of the Americas, for instance in South Africa, Australia, and New Zealand. But these were exceptions rather than the rule.
Elsewhere, the Europeans met hostile environments (deserts, tropical diseases) and densely populated areas. Colonial powers didn't settle them. Rather, they'd claim them and set up trade outposts. Improvements in travel conditions and medicine later led them to also bring in troops and administrators in the 19th century. And settlers came too, but there was no large scale state-sponsored migration like in the Americas. The number of Europeans in these colonies was very small. So small, in fact, that some observers quipped Indians could drown the Brits living there were they to spit all at once.
Lastly, there was an exception to the exception. Large scale migrations occurred in North Africa to the point where 1.6 million or so "pieds noirs" came back to France when Algeria, Morocco, and Tunis gained independence. But Algeria was special. It was a French "Département" i.e. part of France proper. Schools were teaching "Nos ancêtres, les Gaulois" (our ancestors, the Gauls) to Algerian kids. While it's also called colonialism, it's tempting to file it under cultural conversion, cultural spread, or something to that effect.
My admittedly vague understanding of Ottoman colonialism is that it shared traits with the three above descriptions - though mostly the third. The empire itself was culturally diverse, with the Ottomans in control of the administration and the population mostly left to its own affairs. Settlers were sent in its periphery (rather than overseas) to spread Turkish culture. Much like Russia, one might add.
Another factor that made them different is that they were considered the Sick man of Europe until they collapsed. European powers at the time were awaiting when they'd be able to partition the empire between themselves.
Mostly because we are talking about different times and different contexts. I don't know what you have in mind and exactly how you came to this specific comparison but the similarities do not seem that obvious and calling “colonialism” every territorial expansion to dominate culturally diverse populations is not very useful. If anything, the most natural analogies would be with the Habsburg monarchy, the Russian Empire, or Persia and those aren't usually considered colonial powers either.
A colonial relationship is defined by exploitation of one territory (the "colony") by another (the "metropole"). This can involve settlement by citizens of the metropole in the colony at the expense of the colony's native population, but it is not required. More often the aim is to extract cheap labour and raw materials from the colony and to use the colony as a market for the metropole's manufactured goods. Oftentimes the colony will be restricted from direct trade with any other territory (including other colonies of the same metropole!). A good tell-tale sign of a colonial relationship in later times was that the colony would not be represented politically in the metropole's government (or only the metropole's settlers would be represented).
The Ottoman empire does not fit any of the above. It was simply a large multi-national empire, a hold-over from medieval times. An imperial power perhaps, but not a colonial one. It conceived of itself first and foremost as a guardian of Islam, defending Muslims from infidel powers and conquering new territories for Islam when the opportunity arose (though not much of the latter happened after 1600). There's no evidence that its Muslim subjects at least viewed it any differently, and in fact many Arab territories in Arabia and North Africa actively sought to join the empire for the very purpose of seeking protection from the Spanish and Portuguese.
The empire modernized and secularized considerably during the course of the 19th century but still conceived of itself as a unitary state, not a metropole surrounded by colonies. When the Ottomans experimented with constitutional government in 1878 and 1908-1913, all of their territories were allowed to elect native representatives to the Ottoman parliament.
The Austrian empire was similar. It too was a medieval holdover and conceived of itself for much of its history as a protector of Catholicism. It ruled over many nations, many of whom were not happy with its rule, but no one ever refers to them as colonies.
The answer is quite simple. As a historical researcher, the colony term is used as "if a nation or someone's aim is opening trade opportunities -> source. However, Ottoman Empire never conquered any place for the purpose of trade, rather it was all about getting other lands and so in all scientific books, you will see "conquered" term.
Ottomans was planing to get more lands for their religion. Even, their financial system was not directly related trading.
On the other hand, there have never been any evidence that the Ottoman plan was getting precious metals such as gold and silver, or diamonds.
No. Ottomans were not colonial power because they did not colonize outside the continental territories of Europe. They did not get past Aleppo in the South. Netherlands founded and claimed the New Netherlands; Dutch settlers who founded New Amsterdam (New York) and many other cities in New Jersey, Connecticut and Pennsylvania.