里（裏、裡）： 本义:衣服的里层。lining ->内,中。与外相反。inside ->在“这”、“那”、“哪”等字后边表示地点。如：这里,那里。 内： 本义:入,自外面进入里面。enter ->里面。与“外”相对。inside如:海内;关内 ->指某一群体或某一物体的中间。常指国内或朝廷内。inside;internal;interior ->内心。heart ->内脏。internal organs They can't be replaced freely.Such as 里向（inner side）-内向（Introvert） You can get more information by understanding its original meaning.

I discussed with my roommates, all of us hold an idea that in our daily life these two words have no difference in our sproken language . but I looked them in the dictionary ,it said :these two words all mean inside but there are a few differences 里： it used in the concrete things, such as 手里、人群里、水里等 内：it used in the nonobjective things ,such as 一年以内、范围之内 in our sporken language we use “里” more ---- I have a question : are these two wrods right here ? I Mean concrete and nonobjective I want to say 具体的 和 抽象的 thx LOL

里和内是有差别的，这个毋庸置疑。 多数时候不能交换使用。 我心里很紧张= 我内心很紧张。 手里有钱=包内有钱。 里面=内部。 这里=here，和内不沾边。 我书包里有本书=我书包内有本书。 里和内都作inside解时，意思相同，用法不同。 个人感觉，看得见、摸得着、具体的东西，一般用里，其余意识形态类的用内。

i think they have no differences but “里”is used more often and more oral.“内”is more formal and more written. but they all have fixed collocations with other words and cant be interchanged .it is custom.

里 refers to internal space 内 refers to internal affairs (govt) They probably overlap sometimes.