Does anyone know major differences between internal consultancy vs external consultancies from a job duties perspective?

at BP? hmmm

I have been a consultant at BP (from an external consulting firm)...I've never heard of an internal consulting dept - BP are huge purchasers of external consulting support and I'd question the weight/voice that an internal consulting dept would haveIn my experience internal consulting depts rarely make it in the long term because the management team ultimately doesn't have confidence that they bring the best in strategic and operational decision making support. Ultimately they'd rather have the sign off of a large consulting firm..i'd go external rather than internal - much more varied and doesn't restrict you to just one client / industry.

In internal consulting there's a whole set of "job duties" that you don't have - for sales and business development. Resourcing is also approached very differently in internal and external consulting - the job duties for an internal consulting post won't include managing utilisation of yourself or others.