It depends whether you are using the words as countable or uncountable nouns. When used as uncountable nouns, there isn't a difference. For example: Let's make some room Let's make some space There isn't enough room here There isn't enough space here How much room is there behind the car? How much space is there behind the car? When used in this way, they are synonyms. 'Space' is also used as the abstract concept e.g. 'The dimensions of time and space', and of course also refers to 'outer space'. When they are countable nouns, they have different meanings: 'A space' is a gap e.g. put a space between two words 'A room', of course, is a division within a building, as in a living room, a bedroom.

As uncountable nouns, they pretty much mean the same thing. I think I would be more likely to say 'room' if I intended to fill the space in with something and I'd be more likely to use 'space' if I thought the space was going to be unused. This difference is very subtle though, and I think you could always interchange them. Ex. I would be more likely to say "There's plenty of room in the storage shed" than "There's plenty of space in the storage shed", although there's nothing wrong with the latter sentence. If I was in a building with a high roof, I'd be more likely to say "There's a lot of space above my head" than "There's a lot of room above my head", but both sentences are perfectly correct. They're much more different as countable nouns. A space (countable) is any 3D space (uncountable) with defined boundaries. For example, an underwater cave with two large but separate air bubbles has two spaces where you can breathe. A room is a space in a building surrounded by walls. This translates as 'una camera' into Italian. 'Space' is also used to refer the space outside the Earth's atmosphere where the stars and planets are. It's considered a common noun instead of a proper noun and so we don't capitalise it, but it's used just like you would expect for a place name that's a proper noun (I really don't know why we don't give it a capital 's').

Besides I thought the two words had a very different meaning and so it didn't need an example that I actually I didn't have in that moment. Sorry again

Ben, you are absolutely right. It's just I was a sort of lazy I guess. By the way is the first time I post a question fairly vague and without an example. Sorry all guys and thanks for comment

What is the mental habit or learning process that prompts learners to ask questions in a vacuum, without context, such as this one? I don't see how it can.help them improve their English at all. They would still end up writing things such as "There is much space for improvement". What is the difference between "in" and "at"?