  Attractive Bose-Einstein condensates can host two types of macroscopic
self-bound states of different nature: bright solitons and quantum liquid
droplets. Here, we investigate the connection between them with a Bose-Bose
mixture confined in an optical waveguide. We develop a simple theoretical model
to show that, depending on atom number and interaction strength, solitons and
droplets can be smoothly connected or remain distinct states coexisting only in
a bi-stable region. We experimentally measure their spin composition, extract
their density for a broad range of parameters and map out the boundary of the
region separating solitons from droplets.
