if it's easier, I can explain it like this:
You can detect " a " sound in English words like" fan, man, can, tan , etc. " so in Farsi it's the same, in words like " mard ( مَرد ) , fard ( فَرد ), dard ( دَرد ) etc. "
And you can detect " e " sound in words like this " very, hey, etc. " even in the words you said! " ye "
in Farsi these could be detected in words like " yek ( یِک ), del ( دِل ) etc. "
If you find these kind of short words, you may understand the difference between them :)