On Tuesday, December 8, 2015 at 2:13:44 PM UTC-5, wrote:
Is it much more difficult to pass the powered pilot test? I understand that it can be used in lieu of the glider test.

I "believe" you can't take the power written & use it for a glider rating.
The power test's cover things NOT needed in the glider written.

You CAN get a (say) private SEL rating, then do a minimum (of flying time, knowledge) in a glider & do an add-on for the glider.

If you will only do glider flying, then do a glider written and glider check ride.

If you do a glider rating and want power later on, you need to do the written & check ride (sorta from scratch, although some glider time transfers over).