What a great question Gamergirl!
Remember Jane Fonda and the burn? These days we emphasis having fun rather than being in pain and barely surviving a class! At least that's the way it is with Zumba fitness. Don't get me wrong, we work hard, very hard at times (I would die without my sweat band, towel and water bottle!!). It's different though because we're dancing to original music rather than music that is pre set to steady beats per minute with a perfect 32 count beat (in the 80's it was easier to teach, but way more boring for all involved!). The Zumba format enables us to choreograph songs that one normally would not use in a regular class. Basic aerobic classes follow a standard bell curve approach meaning class starts off easy and progresses to a peak and then gets easier again. Zumba classes follow an interval training technique that was introduced in the 90's and now is recognized by the American College of Sports Medicine as being the recommended training technique for both weight loss and heart health. In my classes, we vary the intensity not only from song to song but sometimes even within the song. There is also not so much repetition as we used to do in the 80's. Yet again, zumba classes and interval training are so much better for us in terms of NOT over doing it with 10, 000 knee lifts.... (ok so I exagerate a little but i'm not far from the truth. We see a lot less overuse syndrome. I personally am able to teach so many more classes per week because of the variations of musical genres and moves that I incorporate. Zumba is good to my body compared to the 80's when my chiropractor had to keep my going on a weekly basis!
Another major difference between "then" and "now", especially with zumba classes, is the use of an ipod. My playlists are awesome (if I do say so myself, L.O.L), because I hand pick every single song. In the 80's, and with most prerecorded aerobics music, you were/are stuck with several songs that do not quite motivate you (understatement this time). My zumba playlist makes me smile and go crazy for the entire class, thus truly motivating my students to a new level.
Aerobic classes also have changed since the 80's by the atmosphere. In my classes, we sponsor an atmosphere of love, no judgements passed and everyone is welcome from beginner to advanced students alike. I remember the attitudes that permeated the "air" in the "clubs" of the 80's: pure competition, whether it was the clothing, how high your step was, how hard you pushed yourself, how heavy your weights were....all in comparison with the person next to you! Now, not so much; I speak in terms of Zumba Fitness. My love, my passion. May all in the world try it, and see for themselves. I hope I answered your question without deviating too much into my love of Zumba Fitness!