While I do not profess to have anywhere near the knowledge or experience of Keravnos, Paullus or Meinpanzer, I feel that there is a certain amount of common sense that can be applied to this issue. What is defined as Thureophoroi or Thorakitai, instead of two discrete categories, is actually sets of many points on a continuam of armor or lack thereof, with Thureophoroi being towards the lighter and Thorakitai being towards the heavier, but with a mix.

So here is a possible analysis of the continuam.

Peltastai: javelins, pelte, sword, with or without: simple helmet, greaves, linen or leather thorax.

Thureophoroi: javelins or spear, thureos, sword, with or without: simple helmet, greaves, linen or leather thorax.

Thorakitai: javelins or spear, thureos, sword, helmet, greaves, & one the following: linen, leather or metal plate thorax or mail or muscle cuirass.

So there is an overlap between Thureophoroi and Thorakitai, which is only natural.

This is just my concept based on what I read in this and other threads and my understanding of Hellenistic warfare. If any of this doesn't fit, please correct me so that I can better understand.

Chairman