1) Projects are unique
Projects are unique and have not been done/executed in this specific way before. Business as usual is an ongoing activity and are repeated in the same way on a ongoing basis. An example of this is the design of a new car which will be classed as a project where the ongoing manufacturing of the same car in the same way is business as usual.
2) Projects are temporary
Projects are temporary and have a finite time to produce the deliverables. BAU is a repetitive process where the same things are done in the same way and this will continue indefinitely. An example of this is the designing and manufacturing of a car (the first few) by a certain point in time will be a project while the ongoing manufacturing of the same car in the same way is BAU.
3) Projects produce a product only once
Projects are established to meet a specific requirement/deliverable at a specific time e.g. producing a new smart phone to meet specific requirements. Once the new phone has been accepted as meeting the requirements, the process of manufacturing will be handed over to BAU. The ongoing production of the phone will follow the exact process/steps every time and is considered business as usual.
4) Projects seek step change and transformation
Projects exist because there is a need to change or transform a process / product e.g. replacing an old system (Windows 7) and introducing a new system that will change the way people work (Office 365). This will require a significant change in business process and will be delivered as a project. BAU will seek continuity and consistency and will only allow slow incremental improvements to the process.
5) Projects are funded from a Capital Budget
Projects are often funded from a capital budget and this budget will allow the project to deliver for example a new asset e.g. the construction of a new warehouse. Once the construction is competed and handed over to business as usual, an operational budget will be used to cover the ongoing day to day running and maintenance of the warehouse.