I been inside both cars, the RSX has just a better interior quality. The Celica has a pretty quirky interior and feels like it wraps around you for that "Cockpit" feels.
Both are 6spd, but the Type S comes factory equipped with an LSD.
Both the Celica and RSX have Macpherson Struts front, and Double Wishbones in the rear.
The Celica is slightly lighter than the RSX by ~130lbs.
The 2ZZ-GE actually hits the rev limiter slightly higher than the K20 (8300RPM 2ZZGE; 8250RPM K20). BUT, it depends on which year Celica because they did decrease the rev limit after 2003 I believe. The 2ZZGE has a great feel of that old-school "VTEC KICKED IN YO" while the K20 takes a smoother VTEC engagement. If you want to do forced induction, the K20 has been known to make a lot of power with stock internals than the 2ZZGE.
I don't think you'll go wrong with either car. Just test drive both and see which one fits you.
TL;DR - Flip a coin and buy the car that wins the coin toss.
Isaac Rogers
The RSX-S doesn't have a LSD.
Angel Richardson
Ah, my bad. The Type R had it, I didn't think they would take it out for the Type S.
Seems to contradict you user, at least in the sound of the two cars. I noticed VTAK much more distinctly.
Celica vid had shit sound tho.
Jack Lopez
Don't you Canadians have the Acura CSX Type-S which is basically the JDM Civic Type-R with the Civic Si engine? I'd get that if I was Canadian.
Adam Foster
Type S all the way. It's a great car. The interior is nice and very comfy. Performance is good and handling is PHENOMENOL. Just Google around. There's practically no drawbacks or common issues with these cars. They last and are damn fun. Make absolutely sure to get a facelift model, though (years 05-06.) This is crucial. They look nicer and have several improvements including more HP, and a 6 speed rather than a 5 speed manual. The 5 speed is finicky and suffers issues with gears popping out. Trust me, an 05-06 type S is the best option for an affordable fun car.
Matthew Lewis
This car is LITERALLY a Civic. At least the RSX tries to hide it by being a little different. The 2006 Civic design until ~2012 makes me a little sick. They are more expensive than them for no reason.