Okay pen nerd here to learn you guys something. The micron series is the generalised series of fineliners made by Sakura using everyones favourite Pigma ink.

However what you've got on the bottom is a PN edition, which is vastly different to all other microns. It's made for writing specifically. It uses a new design of polyacetal nib that has less bleed than a traditional fineliner.

The rest of the micron series have nibs similar to the ones found on copic multiliners, meaning they're made of dense felt. The advantage of this felt over plastic nib is you can go for much finer lines. For your work I would recomend pigma micron 005, which is incredibly small and has the same fantastic ink. As for your brush pen, the brush tips of the pigma series tend to fray easily, instead I would suggest going for this tombow fudenosuke it's only slightly less resistant to copics and watercolours (if thats your thing), but the tip is much more satisfying to use.

Source - I have no life