Yarden has the difference below. One has nikud (diacritics the other doesn't. That means just from the writing, you can only tell specifically which is masculine - for pronunciation). it should have been for feminine, kaf sofit, imho, ךְ You can see more under the Pronominal suffixes section: https://en.m.wikipedia.org/wiki/Suffixes_in_Hebrew ) and at https://www.cartoonhebrew.com/chaf-sofit
(note I am learning not a native speaker). This is all in the tips and notes for the course. you can see them at the duolingo website (put your browser in desktop view to see all offerings), or my favourite ways:
organized by skill in one pdf for the whole course: https://www.docdroid.net/JnfmyEV/tipsnotesbackup.pdf
Replace your username where mine is for information on your progress and the tips and notes, etc: https://duome.eu/teribleteri/progress
I am guessing it's because formally, you need the "do" in English to form a grammatical question. In Hebrew there is no additional verb and so this is grammatical (although some people would insist you need האם). So translating something that is formally grammatical into something that is not, is not accepted.
It's not needed but is good to know for pronunciation. I use keyboard app called Swype, there's many others. To learn pronunciation make sure you look at modern Hebrew not biblical. I like YouTube channel linguistix. Fluent forever/Gabriel Wyner & jbs Jewish broadcast /shofar TV both have great videos too. Linguistix: Hebrew Pronunciation for English Speakers: https://www.youtube.com/playlist?list=PLfwqVVFqlT1v0tS9hhTg7kL1cUVyO4oFY
R is ר and is kh is ך. In this unit, we are studying “have”, so יש לך translates to “do you have”, not לר, which I don’t think is a Hebrew word.
Only at the end of the word do you see ך ץ ן ף or ם, and these can be recognized because all of them except ם end below the line.