I would suggest that they are similar, however companion planting is more commonly used to refer to mixed planting of annuals often in an otherwise intensive vegetable bed.
"Guilds" covers a similar concept but would usually be used to refer to perennials. Classic guilds include comfrey under fruittrees - the comfrey mines minerals from deep in the soil making them available for the trees.
Moderator, Treatment Free Beekeepers group on Facebook.
Curse your sudden but inevitable betrayal! And this tiny ad too!
For the Love of Paw Paws Mini Manual - Kickitty-Kickstarter