In fact,

กำลัง (Gamlang) is like "is, am, are + v.ing" in English.
For example, I'm eating means ฉันกำลังกินข้าว (Chan-gamlang-kin-kaw).

While is ขณะ (Kha-nah).
For example, don't talk on the phone while driving means อย่าคุยโทรศัพท์ขณะ(กำลัง)ขับรถ.
In Thai, we can omit the word "Gamlang" but in English you must use "while + v.ing".