Apparently both of them mean "such" and tiel mostly comes together with kiel. I can not fully understand their difference though. can anyone expalin their difference using an example?

thanks in advance
Omid

Ŝi estas TIEL bela = She is SO beautiful
Ŝi estas TIA bela virino = She is SUCH a beautiful woman.
Li kantas TIEL bone = He sings SO well.
Mi estas TIEL forta, kiel vi = I'm AS strong as you.
Mi estas TIA forta viro! = I'm such a strong man!

Just some example sentences there. TIA generally seems to translate as 'such a'... Check out PMEG for a better explanation!

"tia" can also mean "that kind of"; "tiel" can also mean "in that way".

Mi faras ĝin tiel = I do it that way (literally "I do it in that way")

Mi havas tian hundon = I have that kind of dog.

Mi estas tia viro = I am that kind of man / that sort of man

"tia" describes a noun (tia hundo, tia viro). "Tiel" technically describes a verb (mi kuras tiel) or an adjective (tiel bela).

So if you have a question in your mind, you can also ask yourself, "Am I describing a verb, an adjective, or a noun?" and choose tiel or tia accordingly.

From the lernu dictionary:
tia = of that quality; of that sort
tiel = in that manner, in that grade/level

So:
Mi estas tiel bela kiel vi = I am as beautiful as you (I am beautiful at the same level as you; we have the same "level" of beauty)

Mia hundo estas tia, kia estas la lia. = My dog is the same sort as his (lit. My dog is that sort, which sort his is)

Thank you so very much dear Erinja and Chainy. I appreciate your help. It was comprehensive. Thanks again