I have a page with many tabs, and each tab have contents with fields, tables, etc. I want to add each tab contents in a separated page Or a VF component because of the huge number of code lines. But I don't know what the difference between them and when to use each of them and in this case which better to use ?
I am not entirely sure, but I think if you use it as a component then it is included in the page before it is loaded (kind of compile/translation time inclusion) while including it as a page will be a runtime inclusion. So in that sense including it as components will make the page load faster, where as apex:include might be a little slower.