Diferença entre ''near'' e ''by''

Eu encontrei essas frases com by e nao entendi o sentindo dessas frases
Where is the painting?
Primeiro eles colocaram
You talk about where things are. You say: near
The painting is near the window.
E depois :
You can talk about where things are a new way. You can say: by
The painting is by the window.
The painters are by the theater.
qual a diferença entre near e by