These “R2” styled droids are best suited to work indoors and in urban areas. One of these is a military surplus unit as shown by its dull green colour scheme. The other is in a more normal cilvilian colour scheme. They are mainly used in techical work.
Tracked work-bots can perform all sorts of tasks, and their motive type makes them one of the best suited for outdoor work as they can cover a wide area over rough terrain at good speed. They’re also very durable. As you can see here, one of these droids is very old, rusty & battered but is still going strong.
I believe the smaller robot is quite good with plants (for those who haven't seen it, take a look at the film "Silent Running"). It's a bit clumsy at times and walks with a bit of a waddle, but it's a hard worker.
An excellent little group of robots from GZG, you get 2 of each type in the pack. I haven't shown the other 2 duplicates here as they're still part way through painting.
The other figures are GZG technicians/crew for scale, from pack SG15-V04.