Prophetic revelation is connected to a messenger whose divine commission and trustworthiness are established by independent proofs. Inspiration in the present discussion refers to an inward meaning experienced by someone who is not a prophet. Equating their authority would erase a foundational distinction.
The authority of prophetic report depends on established prophethood and reliable transmission. An ordinary person's inner experience does not satisfy those requirements automatically. Even the Qurʾānic use of waḥy for a bee does not erase this technical difference.
The practical consequence is that a person’s private inspiration does not become a new independent source of religious legislation, however strongly the individual may feel about it.