"I have one tomato."
Translation:יש לי עגבניה אחת.
They're the same word. The norms of spelling, when writing without nikkud, change over time, and also there are slight differences that are due to personal taste. Some people like to write it this way, some prefer the other. I think I mostly see עגבניה but maybe not everyone will agree.
It's feminine, he's not referring to male as in masculine or the opposite of female. Instead he's referring to a Hebrew term for writing diacritics: https://www.hebrewpod101.com/lesson/absolute-beginner-questions-answered-by-your-hebrew-teacher-4-niqqud-vs-ktiv-male/
Tuffyboy: They are backwards usually when you're in mobile view. Make sure your browser is in desktop view/ mode. This will also allow you to see the other duolingo features like discussions & timed practice. (From discussions you can search for all the discussions in this course; like this one you're reading now, as well as see general duolingo discussions). If you can't see discussions on the main screen - once logged into duolingo, you're not in desktop view.
If they are still backwards, switch your browser or use the app.
18 August 2019