Prinicipal component analysis vs principal factor analysis

[Mark R]

What is the key difference between these two techniques? And why should I use one over the other?

I'm reasonably familiary with PCA, and have used it for a pilot study I'm doing - but most of the published work has used PFA, and I'm not quite sure what's different.

 

[L00PY]

First Google hit.

Principal factors vs. principal components. The defining characteristic then that distinguishes between the two factor analytic models is that in principal components analysis we assume that all variability in an item should be used in the analysis, while in principal factors analysis we only use the variability in an item that it has in common with the other items... In most cases, these two methods usually yield very similar results. However, principal components analysis is often preferred as a method for data reduction, while principal factors analysis is often preferred when the goal of the analysis is to detect structure.

PCA for data reduction. PFA for communality too.