Incremental where you need to stop and restart running is still much slower than hot-edits (as in editing a dynamic/script language file) or hot-reloading statically compiled as C#). So clean build, incremental build+restart, incremental build while running I think is the 3 levels. I wonder if what the article is on about wrt. smalltalk is the last one.
You could maybe distinguish between "incremental build while running" and "no build, just interpret the code directly". But I don't think there's a major difference between those in practice, it's all just a question of how quickly code edits are picked up.
