Is there any difference between YW, yw, Y W, and y w when texting?

Typically, it is not meaningful to differentiate between YW, yw, Y W, and y w. All of these variations are acceptable to say “you're welcome”. Word capitalization and spacing generally rely on the typing style of the individual, the setup of their keyboard, or the system they are using. The lowercase “yw” is particularly frequently used in informal online communications.

For more read - https://slangspot.com/yw-meaning/