ambient light is ambient light
point light is point light

ambient means environment, or is a word related to environment... something like that
so an ambient light is a light that affects EVERYTHING equally

point means.... point... in our case, it's a point in 3D space
at that point rays of light are shot out in EVERY direction and it acts as what you'd expect a real ray of light would do. so point lights can cast shadows


i wasn't aware that three point lighting would work in an indoor environment

at least not to create realistic lighting. indoors usually have artificial light sources or have windows where natural light sources can come through. which means you have way more lights to deal with than just two directionals and a point light...

i could be wrong though :p