what are the major differences between the IEEE 1363.1 NTRU standard vs. the NTRUEncrypt NIST PQ submission
The only differences would be the parameters that are standardized. This answer gives one parameter set, specifically EES1087EP2. Unfortunately, the IEEE Std 1363.1-2008 document itself is behind a paywall, so I am unable to view the other parameter sets. It seems like at least some of the parameters are the same. In particular, NTRU-743 from the design document submitted to NIST has $N = 743, q = 2048, p = 3, d = 247$ (see table 1), which is the same parameter set as one standardized in 1363.1, according to an analysis of parameter sets (see table 3).
On the upside, there are public implementations which use the standardized parameters, so those can be consulted. It looks like the version of NTRU submitted to the competition comes with only a few parameter sets for evaluation, which may change later on in the contest. The IEEE, on the other hand, standardizes a large number of parameter sets for NTRU.
Is there a difference in the parameter sets to enable PQ security vs. the parameters in IEEE 1363.1?
The parameter sets are chosen to maximize security, not to maximize post-quantum security in particular. Secure parameters will be secure against both classic and quantum algorithms. I do not believe you can construct parameters for NTRU that are secure against classical computers, but insecure against hypothetical cryptoanalytic quantum computers.
Table 5 in the above-linked design document compares the lattice strength for various parameter sets under the best known classical and quantum sieving algorithms.
Is it correct to claim that the IEEE 1363.1 is PQ secure as well?
Yes. All unbroken versions of NTRU use lattice-based cryptography, which involves mathematical problems that are not known to be solvable using a quantum computer. If the IEEE version is PQ secure, then the NIST PQ submission should be as well, and vice versa.