With the PINs, BBM lets you pick and choose who you want to chat with at any point in time unlike WhatsApp which basically allows anyone that has your number to chat with you. On my BBM I've got about 41 contacts in constrast to 233 contacts on my WhatsApp. I think WhatsApp needs to seriously consider having an invitation system.
2. News Feed
In having a news feed, BBM allows for better interaction with your contacts, tou get to know when they change their status or display photos and also comment on them which is great for engagement. WhatsApp on the other doesn't have none of that, and if they did it would be a nightmare for me with the number of contacts I've unless they could come up with a way of letting you pick your favourite contacts.
BBM has its roots from a security focussed company and it's no surprise that it has always supported end to end encryption something that WhatsApp is just adopting. BBM has got a private chat feature which allows one to chat in a secure and anonymously which gives little away about the identity of participants by removing their names and profile photo, and it also deletes the chat after a period of inactivity.
Besides Private Chat, BBM also supports ephemeral messages just like Snapchat which could help one keep their certain sensitive photos and videos private.
4. Message Retraction
If you have ever sent a message to the wrong contact, then you should appreciate this nifty feature. There's nothing more embarrassing than having to explain to someone that the message you sent to them was actually meant for someone else. BBM tops WhatsApp with this by letting you unsend your messages which is great especially when the other party hadn't seen or read them yet.
5. Message Editing
If you are a human being, at least you would definitely have a need for this nifty feature. The message editing allows one to edit messages that have already been sent or delivered to the other party. It saves one the time of having to rewrite the message by just correcting the original text.