What is the difference between Messiani and Christian?

The only difference is that Messianic Jews believe that even though they converted to another religion, they are still Jewish in their hearts.

No Jews who practice Judaism believe that Jesus is the Messiah, and in fact, do not even believe in the same definition of the Word Messiah, while Messianic Jews and Christians are waiting for Jesus's second coming. Most Messianic Jews still perform certain rituals and traditions of the Jewish holidays, while believing in their application to Jesus Christ.

Messianic Jews are not recognized as Jews by either Christians or the Jewish community. Furthermore, Messianic Jews do not qualify for Immigration to Israel under the Law of Return.

Messianic Jews do not participate in inter-denominational Jewish events or news publications.

Studies in the 1980's show that the children of Messianic Jews do not identify as Jews at all, because they are not raised with a strong rabbinic tradition; rather, they see themselves as purely Christian.