My friend and I want to do a play through and we can't play LAN but maybe but if we have the same exact stuff can we use mods on realms servers. How can I do this?
You can't install mods on realms.
However, if the mods are relatively simple (IE: stop endermen from picking up blocks), there might be a way to achieve similar things with command blocks. Otherwise, you're stuck with 3rd party hosting.