- aural - oral
- discreet - discrete
have same pronunciation but different meanings, therefore, they are homophones, whereas, the following are minimal pairs because they are different in one phoneme,
- ascend - assent
- prescribe - proscribe
|Venn diagram showing the relationships between homographs (green) and related linguistic concepts|
Image from Wikipedia
As for "restful - restive", they are sort of antonyms, meaning they are words of opposite meanings, whereas "flammable - inflammable" are synonyms, meaning they are words of similar meanings.
Lastly, "ingenuous - ingenious", they are different in spellings, different in pronunciation, different in meanings, outside of the minimal pairs region, so, they are just confusing words.
Just in case you wanna meet some faux amis, do check out Culture & Usage: "Lufsig", False Friends & Bad Words.
Culture & Usage: "Lufsig", False Friends & Bad Words @ Locky's English Playground
13 Words That Sound Sexy But Actually Aren't @ YouTube
Words You're Probably Mixing Up @ YouTube
13 Foods You're Pronouncing Wrong @ YouTube
Homophone @ Wikipedia
Minimal pairs @ Wikipedia