Some other differences include that Mahayanists feel that it is perfectly OK to break your vows if it is done to help others. For example, if you know someone who drinks a lot, it is OK to have some drinks with them to befriend them and possibly bring them around to the path.
If you are going to criticize the Mahayana, try to do it accurately, rather than with such a caricature.
It was taught by my old Vajrayana teacher, who was a "Khenchen". From http://www.bodhitpath.org
, "The Kagyu, Nyingma and Sakyapa schools use the title of Khenpo for those who have achieved the highest levels of mastery in Shedras. Why? The reason is that in Tibet, the teachers who achieved such mastery also were the ones who gave the monks vows."... "Khenpo is a term in the vinaya meaning "the one who gives the monks vows"—one who has demonstrated the highest vinaya conduct and has become very accomplished, a senior monk. Khenchen means "Senior Khenpo"." So you can see he was very well respected.
It was also a common example used in Vajrayana circles to demonstrate how your Bodhisattva vows supercede your, what they called "hinayana" vows.
The difference in the understanding of emptiness is vast. Even among Mahayanists there is great debate about it and different schools that believe different things exist, yet they all think they have the right understanding of emptiness. There is a doctrine of "Two Truths" which basically says that there are two levels of reality. They are the conventional and the ultimate levels (this is borrowed from Theravada and other earlier sects) but they define these much differently than Theravada did. They say that on the conventional level, things are impermanent, dukkha, and so on and that actions have effects, but that on the ultimate level, all things are dream like, not real manifestations.
This is a distortion of the two truths. If there are Mahayanists who hold it as you say, they are not indicative of the Mahayana as a whole.
While there is much for which one might criticize the Mahayana, it is best to accurately portray that which you are criticizing. It is also worth keeping in mind there is also much within the Mahayana that worthy and of great value.
Simply read about the "two truths" and Madhyamaka. It is all contained therein. I have not inaccurately displayed how they approach emptiness.
Whatever an enemy might do to an enemy, or a foe to a foe, the ill-directed mind can do to you even worse.