Chanukah Menorah
After the destruction of the temple someone found some oil and a lamp. There was only enough oil to burn the lamp for one day, but it lasted for 8 days. This miracle is symbolized by the eight candles of the hannukah menorah. The extra candle is only to light the other eight.
This type of menorah is called a Chanukiah.
The Temple Menorah
The temple menorah has seven branches. Its form is commanded in the Bible in Exodus 25:31-40. The meaning of the form is up to religious exegesis (interpretation) as the Bible does not explicitly explain why there are seven branches.
The temple menorah is often used as a Jewish and Zionist symbology of affiliation and faith.