jandros,
I don't know your entire cruising history...but, if it's just those two Carnival cruises and the upcoming Celebrity Eclipse cruise tomorrow, I really think you will notice the major differences...
Of course, I won't debate that a lot of folks enjoy their Carnival cruises...I mean, what's not to enjoy? they feed you, they entertain you, they take you places and they wait on you and clean up after you...beats being at home and going to work every day...But, all cruise lines do those things...some do them better than others...IMHO, Celebrity does it much better than Carnival...
OTOH, if what one is looking for in a cruise is a lot of folks making a lot of noise, drinking, getting loud...they might prefer Carnival...Celebrity may be a little too refined for them...everyone's different...
What we did see on Carnival were a lot of rowdy younger people, a lot of bachelor and bachlorette parties...it was sort of like going to Circus Circus or the Excalibur in Vegas, but on a ship...OTOH, there are many folks who like just that...
Personally, I loved the Eclipse...and I'll be back on board next July...
Enjoy tour cruise...Come back and let us know what you thought...
Bon Voyage...