Here is the subtle difference in the sounds. But when it uses with some words in some situations - I can't hear the difference too, even though i'm native Russian speaker. You can emphasize this word intonation, and people will understand what you said "эта". Without the highlight tone, they may consider what you said "это". Here is a service of pronounced words (spoken by native speakers), maybe it will help you:
I'm sorry, but I opened both links in separate tabs and went back and forth, listening to a few from one, then a few from the other, back and forth, and there was no discernible consistent difference between это & эта. It has to depend on some context or a kind of intonation which is missing from a computer-generated voice.
Here's a comment on this from r/russian:
из generally has the meaning "out of", so from inside; от, on the other hand, is generally "from" in the sense of "away from". Thus, из здания is 'out of the building', but от здания is 'from the building' - выйти из здания is 'to walk out of the building', whereas 'в двух метрах от здания' means 'two metres from the building'.
My answer, "Эта птица из Европы" makes perfect sense: "This bird [as opposed to that bird] is from Europe".
Just watch the bridge scene from "Monty Python and the Holy Grail" and you'll understand what I mean.
Both Это and Эта should be accepted here, but Duo has turned off reported эта птица as correct.
It's genitive. Here's a list of prepositions, their meaning, and the case of their objects. Some prepositions have objects with more than one possible case (mostly regarding motion or location). https://forum.duolingo.com/comment/28544274
Once you know that it's singular genitive, you can work backwards to figure out the nominative ending.
One "trick" I use is to enter something like "my Europe" in Google Translate, which will give me моя Европа. That tells me by the possessive pronoun that's it's definitely feminine and gives me the nominative spelling. It doesn't always work, because sometimes Google gives a different word translation from the one you're using, but some creative word-entry can usually get the answer.
And here's a declension table of noun endings to help with that: https://forum.duolingo.com/comment/29038061
Found this info:
If you would use 'в' to go to something, then use 'из' to go away from it. If you use 'на' to go to something, then use 'c' to go away from it. If you use 'к' to go to someone, then use 'от' to go away. a way to remember it for english speakers is "business cat" в-из на-с к-от.
из generally has the meaning "out of", so from inside; от, on the other hand, is generally "from" in the sense of "away from".
Thus, из здания is 'out of the building', but от здания is 'from the building' - выйти из здания is 'to walk out of the building', whereas 'в двух метрах от здания' means 'two metres from the building'.
Hope it's useful for someone!