Super Mario Galaxy – Differences When Playing as Luigi

After completing Super Mario Galaxy with Mario, you gain the option to play through it again as his brother, Luigi. I've noticed some slight differences between the 2 plumbers, and have been wondering lately if I've got the whole story.
What I've noticed so far is:

Luigi slides on his heels, as opposed to coming to an abrupt stop when the analog stick is released.
When doing a spin attack underwater, some of Luigi's air is drained per each spin, where Mario's is not.
Luigi gets 20 1-Ups from Princess Peach's letters, where Mario gets fewer.

Are there any more variations in gameplay between the 2 brothers? I'm looking for a complete list of variances.

Best Answer

Alright, I've done some further digging, and these are the differences I've found:

Uses Air when spinning underwater
Has less traction, so he slides and skids
Jumps farther and higher; runs faster
(perhaps related to the above) knocked back slightly farther when hit, which equates to a longer post-hit stun
The cosmic Luigi challenge runs take advantage of Luigi's physics, which may mean separate routes than cosmic Mario
In addition to the above, some galaxies have slightly altered levels, such as the "Luigi meets Luigi" star in Toytime Galaxy, which changes from the 8-bit Mario planet to the backside, which features an 8-bit Luigi (with the change in colors coming from a change in the platform "pixels")
Mario gets 1-ups from Princess Peach's letters, but Luigi gets 20 1-ups instead (It still says "Dear Mario" Poor guy can't catch a break)