This will be a very, very simple guide. I’ll be comparing Pita Ten Volume 1 manga with Pita Ten Volume 1 light novel through pictures.

Light novel on the left, manga on the right
– size of light novel is smaller
– different author. This light novel story is different from the manga
– since this is a text that has been translated into English, it reads left to right. In Japan, it would be right to left

Manga
– despite being already translated, manga still reads from right to left
– Japanese comics

Light novel
– Words, with an anime drawing every now and then
I hope this was a little useful! ^^