Avg Transaction RT as quoted at LR, JMeter

Hi,

I would like to know about :

What is the Average Transaction Response Time as quoted by the below tools:

LR--> Is it FIrst byte of request to last byte of response.

Jmeter--> First byte of request to first byte of response.

last bytes

I am pretty certain both cases are to last byte of response. I am 100% certain that is the case for LoadRunner, and slightly less than 100% for JMeter