"dim" implies low light levels. Something can be indistinct even in good lighting (e.g. it is a long way away, its outline is hard to discern, etc).
"dim" (in the sense I assume you intend) and "indistinct" are adjectives, while "blur" is a verb or noun, so they cannot be directly compared. Probably you mean "blurred". "blurred" describes a specific type of effect; see these examples: