What's the difference between losing weight and getting skinny?

I understand the conventional wisdom for losing weight is to eat healthily and exercise. But that only works to a certain point. It’s not like if you continue to eat healthily and exercise, you continue losing weight indefinitely. And I know plenty of people who do both of those things religiously but aren’t skinny, as well as skinny people who do neither.

So I think there must be a lot of other factors—sleep, stress, type of calories you eat, and…other? What else contributes to determine the rate of your metabolism? What does that even mean, anyway?