Difference between pipe in via $int_if and pipe out via $ext_if

[Stanislav Kruchinin]

Let's consider shaping of traffic that comes from internal network.
I can do this using pipe for outgoing traffic on external interface
# ipfw add pipe 1 ip from 172.16.0.1 to any out via $ext_if

or for incoming traffic on internal interface
# ipfw add pipe 1 ip from 172.16.0.1 to any in via $int_if

Is there any practical difference between these rules?

I've read ipfw(8) manual but didn't found anything about pipe implementation. 
It's a token bucket, right?