Yep
Think of a part as a “kit”, which contains all of your sound settings—sample slot assignments/parameters, FX assignments/parameters, and scenes.
With Model:Samples you get one “kit” per pattern, which has the benefit of being able to have completely different sound settings per pattern.
On the OT, you get 4 parts per bank. This means that your sound settings apply to all patterns within that bank that are assigned to the same part.
With parts, there is the limitation that you can’t have each pattern in a bank have completely different sound settings (unless you’re very thorough with parameter locks), but you do have the flexibility of being able to make a few variation patterns (ie. different trig data in the sequencer), all using the same part, and thus be able to change sound settings and have all of the other patterns follow.