Rather has its many uses. Rather than, a derived phrase acts as either conjunction, or a preposition.
This tablet comes in grey rather than in gold.
As a conjunction, parallel grammatical constructions appear on each side of rather than. When used to coordinate verbs, it indicates that something is done in place of something else, and the verbs are inflected in the same way. It is also used to join nouns, adjectives, adverbs, or prepositions in the sentence
- He decided to call rather than text.
- I drink coffee rather than tea.
- He bought red rather than green peppers.
- She eats slowly rather than quickly.
I prefer to take the bus to work rather than going by car.
This sentence has the same explanation as the above one. In both these cases, rather than is acting as conjunction. While used as a conjunction, we do not use a comma to separate the sentences.