meaning - What's the difference between "obscene" and "scatological"?

This question was inspired by the Malvolio's answer to this question.

1. What is the actual difference? In English-Russian dictionary there's almost no difference if speaking about tricky phrases. And according to Malvolio's answer there's a big difference in meanings of these two words.


2. How to chose when to use "obscene" and when to use "scatological"?

Answer

"Scatological" is only ever used to refer to feces.
Although @Malvolio makes a distinction that "obscene" specifically refers to sexual content, that's not necessarily the case:

–adjective
1. offensive to morality or decency; indecent; depraved: obscene language.
2. causing uncontrolled sexual desire.

3. abominable; disgusting; repulsive.

We (Americans, anyway) often use "obscene" to simply mean "outrageous":

He made an obscene amount of money
selling sub-prime mortgages.

Despite Freud's conflation of money and feces, I can't imagine ever saying "a scatological amount of money."