PLA—or Polylactic Acid—is a completely different kind of thermoplastic. It’s being made from corn starch or sugar cane and is biodegradable, so it’s more environmentally-friendly than ABS. It melts can melt at a lower temperature between 190 and 210 degrees and doesn’t smell bad when it does. In fact many people like the smell of hot PLA. I’ve even read that people refer to it as the smell of waffles—but they probably have never been to Belgium.
Because PLA flows a little better than ABS, you can print more detailed objects with it at higher speeds. It’s especially good at producing sharp corners. It also is a lot less prune to warping, so you won’t necessarily need a heated print bed to print PLA. However, if you want to print objects with a large flat bottom surface without the edges warping a bit, a little bit of heat (around 60 degrees) from the bed can counter this. PLA prints have a relatively glossy surface compared to ABS, but the amount of gloss depends on the vendor, color and print temperature.