Enthusiasts want to know how late a bus is running, whereas Joe Public just wants to know when it's going to turn up.
Arriva's app allows you to do both. In the journey planner mode, it'll say your bus is due at 16:45 (+2) for example. Although I'd have personally designed it to just state 17:47. Giving details that it's running 2 minutes late only when you expand that particular trip. There's actually no indication what the +0, +2, etc refers to, unless you start digging through the FAQs.
Then livemap of course allows you to see exactly where the bus is, and then get the same details for that trip, as you would via the journey planner mode. The map is nothing more than a bit of a novelty really, and it takes some knowledge of the bus network to actually scout down where the bus is on route.
