Are solid and hydraulic lifters visually different? I always thought hydraulic lifters had the snap ring in them but I have a set of big block solid lifters that came with a new cam I bought that have a snap ring (unless I was given the wrong lifters when I bought the cam). I also have a used small block cam I bought from a guy years ago that is supposed to be a hydraulic cam but it's lifters don't have a snap ring. Both sets of lifter are the same height. Just trying to make sure what I have is what they are supposed to be as I don't think I am going to be using either one and will likely be selling them. Are there any other visual differences between hydraulics and solids?

Definitely different looking, Mopar had two different size and type of both solid and hydraulic lifters, 1966,(maybe 1967 and earlier) and earlier had 1/4 inch cups in them and two different cup heights, hydraulic lifter cup are higher.
1967 and later use 5/16 cups but the same on the cup heights being different.
The solid don't have any guts in them, the hydraulics lifters do You can remove the retainer rings, snap rings and look inside to see if they are solid or hydraulic lifters
Let us know what you find

I have worked on cars for a long time and always solid or hydraulic they had a snap ring to take the lifter apart and clean or just check out what it was. The other day ZI took apart a big block chevy that had lifter noise and those roller lifters had no snap rings, they had a solid ring pressed in place no taking them apart. They were supposed to be a hydraulic roller lifter but even after they had sat for several days you could not compress the plunger.

There are soild lifter that have a snap ring and those that don't, they are made both ways depending on the manufacturer.