I assume that the rounds were interchangeable?
Assuming that both weapons were chambered for 7.62 NATO then yes, rounds were interchangeable.
The L1A1 SLR is often referred to as the "
Inch" FAL because it was built under licence in the UK to imperial measurements. The Argentine FAL were "
Metric" and built under licence in Argentina.
From memory, the magazines of
one version can fit both weapons but the magazines of the other version can fit only the weapon for which it is designed. But I can never remember which way around it is.

Someone might know.
Edited to add: Having re-read my post I'd like to clarify that I am not an SLR bore. I'm a Lee-Enfield bore.

There is a difference.