Is 4th edition good for learning 5th edition

A while back I got into D&D at a young age but didn’t get far into it before it faded from my mind. Recently (last week) I got back into it after watching some YouTube videos which cleared up a lot of issues I had with it at the time. That being said I bought a D&D book a few months back for forum roleplays I was into at the time. The book is the Player’s Handbook for the 4th Edition. Since the latest is 5th Edition and it will be a bit of time before I can get a copy of the three books (Player’s Handbook, Dungeon Masters Guide and Monster Manual) would it be efficient to read the 4th Edition Player’s Handbook to learn how to play D&D or would that be a waste of time considering how much I’ve heard about the difference between 4th and 5th edition?

What’s a good cooperative drawing tool to use for an online game? [closed]

In offline games I liked using a piece of paper to sketch stuff and to use as a simple battle map. I’ve recently started playing over Discord and am missing the option to just draw something. What I’m looking for is basically MS Paint for cooperative drawing. I’m not interested in using some kind of grid system or a sophisticated drawing program. If the software would work across platforms it world be ideal, but I would also settle for something that is phone or Windows only.