Coalescence This is a noun. Coalescent This is an adjective. Coalesce This is a verb which in a sentence can be a verb intransitive, or a verb transitive.
It's most commonly used as an intransitive verb, which means that it doesn't have an object. Things that coalesce join with others to become one singular unit. ... Luckily, you can make things coalesce, since the word can also be used transitively (meaning that it applies to an object). Transitive verbs have an answer to the question who or what. If there is no direct object then the verb is transitive whereas if there is no answer to the question who or what then the verb is intransitive.
Hence, it is an issue of how you want to use this word in your sentence which will determine whether you choose to use the noun, the adjective or a verb. But, as you say, they mean the same but grammatically you need the correct form of this word.
