Exterior solid stain v. paint - can someone explain the difference?

[Jean Bolger]

I understand that a transparent stain sinks in to the wood, and a paint does not. But a solid stain doesn't seem to sink in to the wood either- how is this different from paint? Is it just thinner?

I am presently scraping and prepping the wood on my back porch and hot tub surround. I'm pretty sure solid stain was what was on there before. It doesn't peel like paint, it's more just like little flakes. It has worn away to bare wood in some spots. Can I just scrape and recover with a different color?

I've made mistakes before by not priming and by using the wrong type of primer so I'm trying to get the skinny on how not to screw it up this time, lol!