If its the same as last year, it is not the same thing. Waitlisted candidates are ranked higher than alternate list. Look at the official letter they sent you, it will say if you are waitlist or alternate. Towards the very end of the interview season (like June or July) I believe they begin further subdividing the WL into higher and lower ranks, while the alternate list remains in one single pool. Again, if its the same as last year, most (but not all) people who are on the WL tend to get accepted. People from the alternate list also get accepted but it tends to be at a lower rate.
I know they make it unnecessarily confusing, idk why.