'Inside' has the same meaning as 'in'. 'Within' means not beyond the borders of a certain place. For example 'Students may only use this sports equipment within the school grounds' means that students should not take the equipment beyond the school gates or walls. 'Within' can also be used, with the same meaning, to refer to time. For example, 'Refunds must be claimed within 28 days of purchase'. This means that you cannot claim a refund beyond that time.

Look Amira, I know you might expect an answer from a native speaker, however, let's have some discussion before the arrival of that native. Within (adverb only): used before a certain time or period for example: We should have the test results back within 24 hours. Inside (adverb/adjective/preposition): means in/into as if it part of it like for example: It’s raining. We’ll have to go inside. OR She could feel the baby kicking inside her. Hope this was somehow useful. Source: Longman Dictionary. Good day, Mohamed.

"...Lay down all thoughts, surrender to the void It is shining, it is shining Yet you may see the meaning of within It is being, it is being..." "Tomorrow Never Knows", THE BEATLES The usage of the "inside" here is inappropriate.

There are always exceptions, but perhaps this may help a little: "Inside a container" => inside a house/car/train/room/pipe/bowl/cabinet. "Within limits" => within 10 minutes/10 miles/some range/some constraint of some kind.