Working of FixedPositionalEncoding and LearnedPositionalEncoding?

[deshwalmahesh]

I get the part where Image is split into P say 16x16 smaller image patches and then you have to Flatten the 3D patch to pass it into a Linear layer to get what they call Liner Projection. Can you please explain how the two types of Embeddings are working. Looked at your code too and looked like a maze to me. If you could just explain in Laymen's terms, I'll look at the code again and understand.
Thanks