'Cikgu' or 'Teacher'?

On my way to the staff room...

Student 1: "Selamat pagi, cikgu"

I nodded.

Student 2: "Eh, itu bukan cikgu, itu teacher bah!"

Student 1: "Oh, ya kan.. Good morning, teacher"

For once I was speechless.

Apa 'cikgu' dengan 'teacher' tak sama ke??? Tak paham aku budak-budak ni! =p