Glide=higher speed on final ?
Power in=lower speed on final?
No you should be on the numbers in both approaches.
The difference??
In the glide you probably have a closed throttle and a steep approach which means you are trading altitude for speed which will depend on the amount of drag you have.
Say for a given descent profile throttle closed, flaps out you are indicating 70 mph!
You adjust that profile steeper and you airspeed will now maybe be 80 mph (too fast)
Adjust the profile shallower and the speed may bleed off to 60 mph.
Shallower profile no problem
tap into the engine energy and you are back to 70mph.
Steeper and there is little you cannot do without adding further drag to steepen the approach without increasing speed.
High descent angle to the ground will also mean a more abrupt flare to stop the descent and make a smooth landing.
Powered approach Now you are sharing the energy use from the airframe and engine you do not have a no go area like you do with the glide approach in going steeper and hence faster.
So you can adjust your profile in a more accurate way.
With the powered approach you have the extra bonus of prop wash (airflow) over the inner wing area, elevator and rudder all in all far better control over your touch down point and better control over the aircraft.
Chopping the power from the engine means you will settle onto the runway.
Smaller flare required to stop the descent from a flatter approach.
Downside in light low powered aircraft?
You are power sharing between the airframe and the engine so should the engine not give enough you can only trade altitude for airspeed which might not be possible or advisable. So it will take a better understanding and blending of the two energy sources as well as the danger of higher angles of attack and drag on a flatter approach especially with low powered high drag aircraft.
Anyone disagree feel free to pull the above apart 
Pace