What are

I am slowly getting back into vinyl. I have purchased several LP's that are 180 gram. What makes these better than a standard LP? What is the best LP as far as manufacturer and label? A friend came over recently and was talking about different companies pressing the same LP-but some are better than others. I'm also embarrassed to not know there are 45 rpm albums out there. I know the faster "tape" runs, the better the frequency response. I assume this is why 45's are better and if so, why are there not more of them out there.