The difference between "cikgu" and "guru"

When we speak directly to a teacher, we address him or her as ‘cikgu’ but when we refer to a teacher when we speak to others, we use ‘guru’.

For example:
“Cikgu, bolehkah saya bertanya kepada cikgu tentang sesuatu?” [Sir, can I ask you something?]
Encik Ahmad ialah guru saya. [Mr. Ahmad is my teacher.]

Hence it would wrong if we say “Cikgu saya baru membincangkan topic ini.” [My teacher has just discussed this topic.]
The correct sentence would be “Guru saya baru membincangkan topic ini.”