The police in Portland were never overrun. Over the course of those 100+ nights they maintained discipline, held their secure perimeters, and succeeded in their mission to keep rioters from breaching e.g. the federal courthouse or their station buildings. In contrast, officers at the Capitol were completely overrun, isolated, and brutally beaten by the mob without hope or expectation of rescue. Some have said that while lying on the ground taking blows, cut off from backup and effectively abandoned by leadership, they thought they were going to die then and there [0].
They also failed in their mission to protect and secure the Capitol. While blame for that rests mainly on their leaders, at least according what I've read in the IG and Senate reports, I imagine it still weighs heavy on each officer.
[0] https://www.msn.com/en-us/news/us/dc-police-officers-speak-o...