Her older dvds-where they say "1 mile walk" or " 2 mile walk" etc. with white backgrounds-the ones that don't use the "Walk Away The Pounds" logo have some different moves used in them that the WATP series don't-such as a grapevine step, etc. The choreography gets a tad trickier on those. They are walking workouts without weights. They are all similar-just go for shorter or longer walks depending on the mile walk you choose.
Her "Firm Up Fast" dvd was filmed during the same sitting as those-and it is a strength training/weights workout.
Her Walk Away The Pounds Series are really in two basic kinds-the ones that use the weighted balls or 2 lb. hand weights...and the "for abs" ones with the belt. One has a little extra work for the upper body...the other for the abdominals. The 1,2,3, and 4 miles tapes are pretty similar-they just go for a longer walk.
Her Walk The Walk videos and Shortcuts videos were filmed at the same time/setting. The Walk The Walk has a cardio walk video...and a total body strength training video with Christian music in the backgound. The Shortcuts videos are 30 minute strength training videos-divided into individual body segments-upper, lower, and abs-but they do not include Christian music or religious tones.
She has the ramp videos now that help with balance as well as strength.
The "You Can Do" series is beginner level dvds teaching basic yoga, Pilates, or stability ball workouts-if you want to "ease into" a new type of exercise before buying other videos on that topic.
Her new series contains "Power Mile" "Walk & Jog" and "Walk & Kick". The Power Mile is a faster paced 1 mile walk for when you are short on time...the Walk & Jog is a 2 mile walk...but more intense with jogging spurts here and there...and Walk & Kick is a walking video with spurts of martial arts/kickboxing type moves to spice things up.
So...there are a lot of differences in the videos while all being similar to the basic concept. If you can do her four basic steps-you know enough to branch out into any of her videos.
Hope that helps,
Aphil