The one on the left is the general dish scrubber. Then the small one that I use to clean glasses & mugs only, so grease or whatever from doesn't get in them. Next the first pass or heavy duty brush. And lastly bottle brushes which are one of the best $2.99 investments I ever made. They just solve a problem (aka dirty water bottle) forever and I love that.
In my experience the best place to buy brushes like these is at Asian supermarkets, they usually have a ton of different ones to choose from, and they are amazingly inexpensive. Still, you can often find them at regular supermarkets and they shouldn't be too much.
Two other things I love about these types of brushes: they tend to last a long time, and when they do wear out, since they're all natural materials I pop them into my city composting bin!