Mechanical vs hydraulic valvetrain

I recently bought a 66 Dart with a 225 in it. The PO said the top end had been swapped to the newer hydraulic style lifters.

Well, the lifters and pushrods were swapped however it's got a solid lifter cam in it. The top end is a total mess due to lack of lubrication I'm assuming.

I'm trying to figure out what rockers and remaining valve train components I have. Can anyone show me the difference between a hydraulic and solid rocker arm? How would I tell which set I have? Mine have a hex adjuster above the pushrod which leads me to believe they're for a solid lifter, but I want to make sure it isn't put together incorrectly this time.

Thank you!