To add onto the comments that you’ve already received, red dwarfs of approximately 0.08 - 0.25 solar masses are thought to be fully convective. So they mix all of their hydrogen fuel down into the core throughout their lives. More massive stars have different layers, the sun has a radiative zone above its core that is so dense it can take tens of thousands of years for a photon to get from the core to being released as light. More massive stars are too dense to mix all the hydrogen down into their cores and so end their lives with a lot of unspent hydrogen that gets ejected during the end of the stars life instead of being used as fuel in the core.

Another fun fact is that it’s thought that stars more massive than our sun have an exterior radiative layer rather than a convectional outer layer and so they wouldn’t have the “granules” that we see on the surface of the sun. They would instead be one “solid” shining surface.

God I love space. So fascinating.

Someone please correct me if anything I said is wrong, I’m merely an amateur space nerd and not a professional.