If we're still talking about the circuit below, then for purposes of how the motor circuit works there isn't any difference. That circuit would usually be a 240V single phase circuit, where "line" is L1 & the other "line" is L2 and both are "hots" and there is no neutral.
If the compressor were rate for 120V instead, one "line" would be L1, and the other "line" would be Neutral, "N", because it's connected to the center tap at the transformer, but for all practical purposes nothing has changed except the voltage.
Don't get hung up on the term "neutral". It's a power wire just like L1 is. It brings power into the run cap just like L1 does. Power comes in thru L1 and leaves thru N, and it also comes in on N and leaves thru L1, alternating back and forth.
Thank you very much. I never really had a thought l1 and l2 had a relevant difference in voltage or function of each other, but I needed to ask. But, y'all have pretty much cleared up the differences between 'hot' and 'neutral'.