In the dictionary the meanings of these two words seem interchangeable so why do the two words exist? Are there different contexts for their usage?
Definitions by Merriam-Webster:
Definition of PERTAIN
1
- a (1) : to belong as a part, member, accessory, or product (2) : to belong as an attribute, feature, or function <the destruction pertaining to war> (3) : to belong as a duty or right <rights that pertain to fatherhood>
- b : to be appropriate to something <which rule pertains?>
2
- : to have reference <books pertaining to birds>
Definition of APPERTAIN
- : to belong or be connected as a rightful part or attribute : PERTAIN