While I'm not a man, my husband has had experience with female dogs and multiple women, and this has been a topic I've asked about before out of curiosity.
Consensus being, on his account, is that it varies. On a base level a dog will typically be tighter than a human. A woman can however do strong pelvic floor exercises (such as kegels and pelvic strengthening yoga for examples) to increase the tightness and overall muscle control she has. He says there's a noticable difference between women that do this and ones that don't take any initiative.
There is a also a difference between female dogs whom have had litters and ones that haven't, and larger to giant breeds will be more loose especially after having puppies. Like women though, they can tighten back up after birth but many will still loose some of that initial tightness. That's not to say they are a hotdog down a hallway. They still have the grip strength, but usually the larger something is the bigger things will be. Smaller breeds will usually always be tighter on average (but please don't do anything with a dog too small for penetration). He said that there has been a few women who were on par with the dogs he's been with, but also said those women were ones that worked their pelvic floor muscles religiously and stayed in shape, and I do certainly enjoy staying in shape!
Something that cannot be changed however is body heat, which a dog will always have a higher temperature of than a person, male or female. Female dogs also have an extra muscle ring at the entrance of their vaginal canal that's used to hold a knot in place. Humans completely lack this and it cannot be replicated. Female dogs also have a specific angle curve in their vaginal tract that humans do not.
He's not had anal with an animal, so he cannot give input on that. If you're meaning anal with a human versus vaginal with a dog, he says it compares to having sex with an ass versus a pussy, like anything else.