Greetings! Interesting question. Learned quite a bit researching templum and it's relationship with aedes. Is this the answer correct?

A templum (plural, templa) was a sacred area. Templa were aligned with the cardinal points with a west-facing entrance. This sacred space was marked by augurs as a suitable spot for divination. It was also a space where people could interact with their Gods for the gods were believed to be present in templa.

The sacred space of a templum did not have to include a physical structure. The modern idea of a temple would be closer to the Latin word aedes, which means building and could also mean temple or sanctuary.

An interesting point brought up in Templum vs. Aedes, an article from Forum Romanum, reveals the subtle differences between aedes and templum:

Important political decisions could only be taken with the consent of the gods, so they would have to be taken in a templum where the gods were present. The Comitium in the Roman Forum was such a templum, and it is also an example of a templum that did not contain an aedes. The senate could only meet in a templum, so if the Curia was not available for some reason, the senate would often meet in a temple, aedes, that was also a templum. Such meetings were held in the Aedes Castoris, in the Aedes Iuppiter Stator and in the Templum Concordiae, all temples in the Roman Forum.

Sources

• Templums vs. Aedes: Ancient and modern use of the word temple
• alt="templum definition from about.com">Templum definition from ancienthistory.about.com
• Templum definition from Real Dictionary's Latin dictionary
• Turcan, Robert. 2000. The Gods of ancient Rome : religion in everyday life from archaic to imperial times. Routledge, New York.