Hours will typically be worse for junior residents, but a lot will depend on how call is structured. In general, PGY-2 is the toughest year. To illustrate, a typical week as a junior taking home call q5 might look like this:
M 6:30am-5:30pm
T 6:30am-6pm
W (home call) 6:30am-6pm, 8-11pm, 2-4am, 5-6am
TH 6:30am-4pm
F 6:30am-5pm
Total = 60 hours
*Weekends can involve a 24hr home call on Sat/Sun anywhere from 1-4x per month, so that could bump it up to 80hrs on those weeks.
Now compare that to a program that takes home call q2-3, and realize that would easily add another 10-20 hours every week.