Same wattage, same amount of electricity used.
Heres some info from another forum that might also be helpful:
" The real difference between a CFL bulb and a T5, or any fluorescent tube, really, is the area covered and the light intensity dispersed through that area. Simply put, a CFL bulb will really "light up" a one foot area or so. A T5 fixture will take the same light and spread it out over four feet - more area is covered, but the light level is lower over any one part of that area. There are other differences - a CFL is more flexible, since you can move it wherever you want to accommodate whichever plants you want, whereas a T5 is straight, all plants under it get more or less the same amount of light (a bit more light in the center, less at the ends), if you bring it up because of one tall plant, you're bringing it up for all other plants. You can more easily move a CFL aside, whereas a T5 will require more permanent installation."