The 1974 outfit (on the left) was sold together in the Horse box and had no special name. The 1976 outfit was sold separately as one of eight different outfits called Fashions For All Occasions and the riding outfit was called Riding Out 44260.
The yellow jumpers should be the same but since Pedigree had a lot of different production lines, some small differences can appear but that should not be due to the year they were made. But the trousers and the boots had differences as you can see on the photo below.