Question : what is the difference between utf-8 or utf-7 both are unicode

In your solution you state to use unicode or utf-8.  Both are unicode, is there a difference and if so, what is it?

Answer : what is the difference between utf-8 or utf-7 both are unicode

UTF-8 Compared to UTF-7

Advantages
UTF-8 uses significantly fewer bytes per character for all non-ASCII characters.
UTF-8 encodes "+" as itself whereas UTF-7 encodes it as "+-".

Disadvantages
UTF-8 requires the transmission system to be 8-bit clean. In the case of e-mail this means it has to be further encoded using quoted-printable or base64 in some cases. This extra stage of encoding carries a significant size penalty. The importance of this disadvantage has declined as mail transfer agents' support for eight-bit clean transports and the 8BITMIME SMTP extension as specified in RFC 1869 rises.

From: http://en.wikipedia.org/wiki/UTF-8 and