I'm doing this off the top of my head, but if I remember correctly, the 744EL is the Drake ADA elongated and the 454CEFG is the Drake II cyclone flush elongated comfort height CEFIONTECT.
I was in your boat a few months back and I went with the 454CEFG. Is it worth the extra +/-$100? That depends on you.
To compare them, the EL and the EF are very close to the same thing; the only difference being a fraction of an inch in bowl height (L=16.5", F=16.125").
The C and the G is where the real difference is:
C=Double Cyclone rinse (2 water outlets parallel to the top of the bowl causing a cyclone type bowl rinse as opposed to the standard many holes facing down into the bowl under the rim)
G=CEFIONTECT finish (a nanotech finish that is antibacterial and helps prevent skidmarks from sticking in the bowl)
some other small dimensional differences:
744: 28" rear of tank to front of bowl
454: 28.5"
744: tank is 19.5" wide (there is an 'ELN' model that has a 18.625" wide tank)
454: 16.5"
