There are differences between the NAUI and PADI NoDecompresion Stop (NDL)
dive systems -- including differences in the tables included in each system.
Whether or not the diffrences are "major" is a question of philosophy,
which I'll not address.

However...  All NDL systems come up with pretty much the same dive times.
Think about it -- if a system gave you much longer times, it would quickly
be found to be too dangerous -- too much of a risk for DCI.  On the other
hand, if it gave much shorter times, nobody would use it -- we all want
the longest possible NDL times.

If you want to compare, get both systems and work various dive scenarios.
This is the only way to understand them.

If I remember correctly- one major difference is:

Naui tables take 24 hours to off-gas.

PADI is 12 hours to off-gas.

No doubt there are others-

IMHO both have proven to be safe(by virtue of lots and lots of dives)

Andrew

Yes, in a nutshell, PADI tables uses only shorter halftime tissue
compartments when calculating NSL on the tables.

Example, do a dive for 60' for 55 min.

In NAUI or it close cousin, USN tables, you cannot do a second 60'
dive after a 1hr SIT.  With PADI you can, albeit with a shorter NSL.
If you look at different SIT in a PADI Pressure Group W after a 60'
55min dive, you rapidly drop pressure groups in just 3-5 minutes.

Yes,  color and labels