They each seem to offer similar services, which include dog sitting (often in your home), dog boarding (often in the sitter’s home), and dog walking. Most such services also conduct some level of background screening or checking on the dog walkers/sitters/boarders. They also both have mobile apps to make interaction with these services easier. There are several differences as well though, which are brought out pretty nicely in this table comparing Rover and Wag. I like tables like this because they make things more easily visualizable.
The bottom line is though, that no matter what service you use, what you really want to do is to get to know the particular individual who will be taking care of your dog. After all, the care that your dog will get will ultimately depend on that one individual, and his or her living conditions if you are boarding your dog at their place. That is the deciding factor – the person involved – rather than the particular service you choose. Because there are good care givers and not so good care givers who work with both services.