A or B

An Hour or a Hour

An hour is the correct and standard form, while a hour is incorrect.
A or B

Attain vs. Obtain

Attain is to achieve a goal through effort. Obtain is to acquire or come into possession of something, typically through external means or sources.
A or B

Hear Hear or Here Here

Hear, hear is an expression used to show agreement during a discussion. Here, here is an incorrect variation.
A or B

Saw vs. Seen

Saw is the past tense form of the verb "see." Seen is the past participle form of the verb "see." "Saw" and "seen" are two commonly confused verbs in the English language
A or B

Requestor or Requester

Requestor refers to an entity making a request in a business setting. Requester is a more commonly used term referring to the person making a request.
A or B

Goodnight or Good Night

Goodnight or Good Night convey well-wishes for a restful evening or sleep, they are employed differently based on the situation and formality.
A or B

Emphatic vs Empathetic

Emphatic is expressing something forcefully, while empathetic is the ability to understand and share the feelings or experiences of others.
A or B

Other Than or Other Then

Other than is the widely accepted phrase used to introduce an exception or exclusion. Other then is the incorrect variance.
A or B

Vender or Vendor

Vendor is a seller or supplier of goods or services, while vender is the less common variant.