Lasko/galaxy box fan Blade swap | the difference between a 4uf capacitor and 8uf capacitor. 

The fan on the left uses the larger 8uf capacitor ‘Sagitta’ motor and has an extremely minuscule rpm boost. The fan on the right uses an unbranded motor that says “PM” on the capacitor which signifies ‘promotor’ (uses 4uf capacitor). The difference between these fans is negligible.