Bonus ink are ink you get from completing reading events, referrals, fortune cookies, promotions, and ink giveaways and normal ink is the ink you get from purchasing or earn by watching ads and completing offers.

The main difference between bonus ink and normal ink is that bonus ink can only be used to purchase premium chapters while normal ink can also be donated to support creators. 

Normal ink that's donated to creators have differrent fees as well.

Ink purchased in the app - 30% fee

Ink purchased on the website - 15% fee

Ink earned from ads and offers - No fee

This basically means that if for example you donate 1,000 ink you've purchased on the Tapas app, the creator you donated the ink to will only recieve 70% of that, which is 700 ink. Also if you didn't know this, 1,200 ink is equivalent to $1 USD. 

Oh, I forgot to mention the mistake in one of my previous episodes talking about the support fee Tapas takes. After looking in the annoucements tab on Tapa's forum, it seems that Tapas has permanently weived the 15% additional fee for supported ink.