# Difference between planar sub-continua and sub-continua on the surface $\mathbb{T}^2$?

Can anyone tell me what is the essential difference between planar sub-continua and sub-continua of the torus? I will appreciate if you can give me some references.

• I am sorry for my mistake. I am interested in continua, it is known that torus is the quotient space of the unit square by pasting the opposite edges together, if $p$ is the quotient map, and $K$ is a sub-continuum of the unit square, what does the image $p(K)$ look like? Or if $L$ is a sub-continuum of the torus, what is the pre-image $p^{-1}(L)$ of $L$? – Yee Neil Dec 18 '18 at 3:08