|There are so many "it depends" that it is impossible to say.|
The speed of each CPU, the hard disk speed, what other tasks each computer is performing at the time, all play a part. The LAN doesn't operate in isolation from the rest of the system.
When you are measuring data transfer speeds you should be using bits not bytes. Bytes doesn't take into consideration of the overheads that are needed which can be as much as 10% of all the data transfered.