These are geographical terms which are commonly mixed up, due to the similar nature of the terms. In brief, the difference is simple - glacial erosion is the erosion process and consequences physically caused by the ice mass itself, whereas a sub-aerial process is caused by the atmosphere and the weather. Glacial erosion produces landforms (macro, meso and micro) such as corries, arrêts, and pyramidal peaks, some of which may be confused with results of sub-aerial processes. On the other hand, sub-aerial processes produce, most commonly, scree.