Both have a .5w setting for bedroom practice, the 100w has an effects loop so will be better at handling pedals. Maybe bring up the features online, side by side, compare the two and see if the differences are worth the extra money, size and weight to you.
Edit: The 100w also takes the GA-FC footswitch where the 50w doesn't.
Edit: The 100w also takes the GA-FC footswitch where the 50w doesn't.