TWO/TO, THREE/TREE

I think the pronunciation for  of TWO and TO is not distinguishable. Please correct me if I am wrong. I have never had any problems using both words either word because they are used in different contexts.

However, I feel there is a slight difference in pronunciation between THREE and TREE. I can not really figure it out how because I always have a problem with the "th" word.

If you can't hear it, it will be almost impossible to say it. Listen, then practice: 

http://www.wikihow.com/Pronounce-'th'-in-English

Find the book,Fox in Socks, by Dr. Seuss — "Through three cheese trees three free fleas flew. While these fleas flew, freezy breeze blew. Freezy breeze made these three trees freeze.."