What's the purpose of collections when you have bookmarks?

I have recently been searching for this same question because I just started using Collections.  I have a ton of Bookmarks and I am ok with them, but Collections is now easier for me.  I am having a glitch I never had before with Bookmarks.  When I go to add a link, it defaults to a folder I am not asked anymore to pick.  I have tried looking at settings and whatnot but for now, Bookmarks are secondary to Collections.  I like their layout too.  The only bad thing about them is if I want to go to another browser and import pages there.  I have been dumping Google and leaving as much of it as I can for MS so I doubt I will use another browser.  FireFox is good, but like its old Netscape, it has an odd or convoluted setup of menus.  That's me, I know folks love Firefox.  So if this all made sense, it to me is a gravitation to Collections and I like what I see.