difference

Question

what is the difference between Aside and Section?

Answer 1

<aside> and <section> (as well as <header>, <footer>, <nav>, and <article>) are alternate names for <div>.
These names were added in HTML5 because divs are usually used for these purposes. Each of them can be interacted with separately in CSS and JS.

Answer 2

https://www.w3schools.com/htmL/html5_semantic_elements.asp

Aside is intended to be used for information that is somewhat relevant to the main topic being discussed, but is held off to the side so it feels more optional to read (like a definition, quote, or advertisement) and less distracting.

Section is good for grouping things together (like if you had 2 paragraphs and a chart on market outlook and 3 paragraphs and a table describing competition, you may want to have a section for each).

All of it is at your discretion.