Difference Between In and inside
It is true that the two prepositions in and inside appear to be similar, however they are used quite differently.
In
‘In’ is used to describe the location of the noun. To cite an example ‘the car is in the garage. Here the preposition ‘in’ describes the location of the car. The preposition ‘in’ is used to convey the location in the direct sense
Inside
The word ‘inside’ is used to convey a sense of ‘depth’. Inside emphasizes the presence of something within something. The word ‘inside’ is used to convey the location in the indirect sense.
Let us have an example- ‘the fish is in the aquarium’ and ‘the dog is inside the house’. There is a sense of absoluteness about the presence of the fish in the aquarium in the first sentence , but there is the sense of abstractness about the presence of the dog in the house.