I essentially want to put two forms into 1 list, some of the items they contain are the same and some are different. I'm not really sure how content types work. I essentially want first for the user to select either Veg or Meat, which will take them onto a form depending on what they selected. I've done a bit of research and believe having two base content types is the best way forward. Just need some explanation on how to go about this, I am using sharepoint 2013
Yes you must use content type for this case!
Go to Site Setting and site content type then Create 2 content type for each them and create them columns!
So create a list and go to list setting and Advance setting so Choice
Allow management of content types? Yes.
Add from existing site content types then add your content type.
Then Go to form setting and then you can customize your new content types form.
I hope that this is usefull!!!