Salam! Alah, this is actually quite common lah, different machines, different sonographers, semua boleh affect the measurement kan, so jangan worry sangat. A few of my mum friends had similar situations, some punya perbezaan even bigger than yours, but everything turned out fine, the important thing is both readings are still within normal range at 36 weeks, so you're good lah. Tapi kalau you're worried, just check with your doctor at the KK next time, they can explain the difference better and monitor closer kalau kena.