Greek adds suffixes to the ends of words, or varies the spelling of a word, to denote nuances of meaning, a lot more than English does. They're still the same word fundamentally.
Is the "accusative singular" form. Accusative meaning it is talking about a specific woman, and singular meaning one. So here Jesus is talking about a man looking at a "specific individual woman" to lust after. But instead of adding the words "specific individual", Greek adds some extra letters to the end which mean the same thing.
Is the "genitive plural" form. In this case, being "genitive" rather than "accusative" means it is refering to women existing out there in general but not focussing on a specific few women as the object of the conversation. So this means more generally just "multiple women".
Note that even in English the spelling of women / woman is changed to show the plural or singular, but it's still the same word with the same meaning. In Greek the spelling is also changed to denote "case" and gender. This is why the same word can be written so many different ways in Greek just to denote minor differences in how it is being used.
This is a complex issue which I am no expert in, and I am sure to have oversimplified it, but I hope that is helpful.