How does a protostar differ from a star?

A protostar is different from a star in that a protostar cannot be seen because it is enveloped in dust. Unlike a star, a protostar does not have any fusion in its core yet.

No. It starts as a protostar.

A protostar is more like a stage previous to a star - before it ignites.

There is not really another name for a protostar. The formation process in simplification is: Giant molecular cloud Protostar T Tauri star Pre-main sequence star (or PMS star) Main sequence star.

A star that is forming is called a protostar.

Protostar. Comment: Or, perhaps it's the nebula from which the protostar forms.

The term is "protostar", not "prostar". Yes. A protostar is an early stage of a star.

A protostar will live as long as 100,000 years. After material stops falling on the protostar it will enter then T Tauri star phase.

That depends on the mass of the proto-star.

No one. It comes from the Greek - proto - meaning first. So first star - a protostar.

through the process of fusion, it becomes a star: the birth of the star is the start of fusion. therefore, it is after fusion that it is classified as a star.

Before a star is born, it is called a protostar.

If you can see it, its a star. Protostars radiate only in the infrared.

That's called a "protostar".

trapping of thermal energy inside the protostar

The pressure within a protostar counters gravity and prevents the star from collapsing further.

a low mass protostar is the begining formation of a low mass star. a low mass protostar is formed by a nebula (stellar nursery), like a cloud in space, where all stares come from. the definition of protostar is: a collection of gas, and dust who`s gravitational pull is causing it to collapse on itself & form a star. a LOW MASS protostar just has a LOWER MASS then a HIGH MASS protostar. Your Welcome:)

The "protostar". That's not classed as a true star, but I think that's the answer.

A protostar is the first building block of the main star. As it has not yet accumulated enough mass to join the main sequence, it will be smaller than the main star. The next stage will be a T Tauri star.

Nuclear fusion reactions begin and the protostar becomes a true star.

A protostar generates energy by friction whereas a main sequence star generates energy by fusion.

A protostar is a star that is in the early stages of formation that has not yet become a main sequence star. A white dwarf is a remnant left behind after a low to medium mass star dies.

It isn't clear what you mean by "the following", but the initial stage of a star is called a "protostar".

A PROTOSTAR is the 1st stage of the formation of a star. Comment : But you could say that the nebula of gas and dust from which the protostar forms is actually the first stage. In that case, the answer is a "nebula".

A protostar is a star that is still forming and has not yet started a sustained fusion reaction. All the heat is the result of gasses being compressed. A white dwarf is the remnant of a dead star that has exhausted its fuel and is much smaller and denser than a protostar.