The solo instruments are chromatic and the PLR instruments are minor thirds.
GPO brass are comprised of individual instruments whereby you make your own sections from the individual instruments. ProjectSAM has sampled unison sections. Two different approaches
For scores that require divisi and separate parts (like a great deal of classical music), GPO has an advantage. For large sectional sounds ProjectSAM is great. I recommend ProjectSAM very highly. If you can, get both. They work well together.