When I go to my SharePoint onliine and on top left corner select app-launcher and choose SharePoint, I can see several site collections some of them are associated to SharePoint Groups and some of them are communication sites. the url for all of them is something like
Question 1: Are these Site collections or sites and what is differents between them? because when I browse to them thay have different layout and navigation.
Question 2: When I go to admin portal
https://portal.office.com/adminportal and choose SharePoint under Admin Centers, I can see all my Site Collections that I created long time ago, but I cannot find none of above Site Collections (Communication and Group site collections), What is differents between these Site collections and those? where are those site collections?