I think the definition of Greater Spawn is pretty clear, people that were ascended by the Apostles themselves or if we stretch things a little, people like Alice and Shen, who were infected by a Chosen. All others like Nico, Zack, Alexis, Nyx and Lucius, should be lesser spawn, meaning anyone infected by Monsters with mixed traits, the power wouldn't be an indicative of being a Lesser/Greater Spawn, as according to Syla, lesser Spawn can become very dangerous, since they evolve in unexpected way.
Other thing that might be a signal of a lesser spawn being one, is them having a very specific/rare power that doesn't fit with the Twelve Traits alone, like Pyrokinesis-Pressure Manipulation, Malik and Bernhardt both being very obvious examples of a Lesser Spawn, and even more prime instances of Syla's mention of how they evolve in unexpected, dangerous ways. There are of course other weird cases that may not fit either classification, Kira for one, she's the Spawn of a Colossi, that are purpose growth Monsters, each with a unique power, and if we go with Eisheth's surprised words when understanding what's spawn Kira is, Colossi might not usually have Spawns, and then there is Henri, he has a Deity/Deity's Power within him, not a mutt like the other Captains but certainly not a Greater Spawn either.