Question all mikrotik routers have same os ? and same GUI interface?

You can be very happy that they DON'T work like iphones. You have to manually download updates they will not update themselves. In addition you might need to download different files for different hardware platforms even though the OS patch level is the same.

These are not simple devices to use and although they have a gui a lot of people use the command line. There are some function that can only be done via the command line. Technically you would do it though the gui but it is just a blank command screen you enter commands in.

These are very close to commercial routers and have many features most people will never use in a home install.