word choice - Difference between おかあさん and ははおや

What is the difference between these two terms for the word «mother»?

• おかあさん


• ははおや

Is there a difference in politeness/register in addressing someone, our some other form of difference between these two?

My dictionary also lists:

• はは


• かあさん


• ははのみこと

as being in current usage.

Also, I cannot figure out why katakana, which is usually used for foreign words, would also be used for two forms of mother, as listed in my dictionary, as follows (please note, I couldn't get my input method on my Android keyboard to input the first of these in katakana as in the dictionary, perhaps someone can tell me how to do it).

• おもに


• ママン

REFERENCE:

Thanks.