Yes, determinations are based on chances of winning + the nature of the role. So sometimes if you have a role that could go either way (Betsy Wolfe, Adrianna Hicks, Sharon D. Clarke), that's a choice based on the producer & actor's preference. If not petitioned, it will be entirely based on billing, so anyone above the title = lead, below the title = featured.
For example, some people thought Josh Gad would be deemed Featured for MORMON, but he was in Lead. Same with the LEHMAN TRILOGY boys and Lithgow in HILLARY & CLINTON. Or Ben Fankhauser in NEWSIES (deemed a Lead).
It's different from the old days when it was entirely determined by billing –– which led to weird category placements: Featured classifications for Maria in WSS, Marian in Music Man, Sarah in G&D, Rosabella in Most Happy Fella, John Adams in 1776, Tammy Grimes as the title role in Unsinkable Molly Brown. Or George Rose winning Lead Actor for Alfie Dolittle in MY FAIR LADY.