Pressure agglomeration relies on extreme pressure to force particles together into a desired shape. This includes the following techniques: compaction, briquetting, extrusion, tableting and molding.
Non-pressure agglomeration, also known as tumble growth agglomeration, relies on a binding agent and the phenomenon of coalescence to create agglomerates. This includes: pelletizing (drum or disc), micro-pelletizing (pin mixer), mixing (pugmill mixer/paddle mixer, or pin mixer), and conditioning.
While there are many things to consider when choosing the best method for your material and processing goals, operating and capital costs are often the deciding factor between the two. In addition, some materials may respond to only one method, where others will respond well to both.