Problem wth separation technique of 3layer architecture

Question

Hi...

I'm trying to make a program using 3 layer architecture, but I have a problem with how I separate the layers. I was try to search in google but still don't understand. If I separate the layers in different project but still in one solution, is it called 3 layer or 3 tier architecture?

Can soemone give me an explanation maybe, or reference about the difference separation technique in 3 layer and 3 tier architecture?

Thank you...