Every teacher has a different way of teaching

The wonderful thing about yoga is that although there are particular poses and sequences that are universal, how a teacher teaches them is infinite. If you are just starting out on your yoga path it is an idea to attend lots of classes just to find out what is for you.

From my experience, if you want a strong class, look for the words Iyengar or Ashtanga. The word Hatha is more likely to indicate a softer approach. If you want to go for yoga in a hot humid temperature, then there is Bikram (not for the faint hearted!). 

My own yoga is very floor based. We tend to be horizontal for most of the class strengthening our core muscles. I wouldn't call it yoga for layabouts, but I might be tempted.

And remember that as you change throughout life, you might want to change your yoga path - climb something more challenging, or go for a flat shady route. That is the magical thing about yoga, it's infinite variety.