Arriving Hong Kong International Airport on Wednesday, April 22 and need to get to Guangzhou.

There is no need to get into HK downtown for a transfer. There are direct long-distance buses to New Tianhe Hotel (near Teemall) and East Railway Station.

To New Tianhe Hotel, the schedules are from 07:30 to 20:30. The ticket fare is 250 HKD per adult. And it takes around 4 hours on the way. After arriving, walk east along Tianhe Road around 385 yards and then you will arrive at Teemall.

To East Railway Station, the schedules are from 08:00 to 18:00. The ticket fare is also 250 HKD per adult with the travel time around 3.5 hours.

Isn't it faster by Train than by bus?

Thank you

Yes, trains are faster from Kowloon to East Guangzhou, it just takes around 2 hours on the way. And the ticket fare of first class seat is CNY165. However, in the case, you need to make a transport tranfer instead of getting to Guangzhou directly from airport.
You can choose the transportation vehicle according to your travel plan.