There are definitely differences. + And - imply addition and subtraction, while 👍👎 imply pleasure and displeasure, or agreement and disagreement. The + and - in this context is quite ambiguous, because it could mean volume up/down, or adding or subtracting the song from a playlist for example. Those would be my first guesses without context I think. Color coding them would help, because it would give more weight to the action, but I think the iconography is still overly ambiguous compared to other options. Source: am professional designer.