What is an adjective for words that rhyme or sound similar?
I think you're looking for phonetic:
Of or relating to the sounds of speech.
As in:
The relation between "node" and "load" is purely phonetic - they just sound similar.
There is a noun assonance meaning that they sound similar, have similar vowel sounds. This exends to more than just rhyming though - starting with the same sound instead of ending with it could count as assonance.