One view is that we should immediately face the direction of the Holy of Holies in the Temple.
Another view is that outside Israel a person should face the Holy Land; if in Israel one should face Jerusalem, in Jerusalem one should face the Temple and if in the Temple one should face the Holy of Holies.
Both sages obviously agree that all prayer ultimately reaches Heaven through the Holy of Holies, but why are the two views necessary?
The answer is that there is always a higher spiritual level a person can attain. A Jew in the Diaspora must acknowledge that there is greater sanctity in Eretz Yisra’el. In Israel one must recognise that there is greater sanctity in Jerusalem. In Jerusalem there is greater sanctity on the Temple mount. Even if one is in the Temple, even if one is the high priest in the Holy of Holies, a still higher level of holiness is possible.
One must never reach a mountain top without seeing a further mountain top ahead.