Overall

Overall (adv) = (1) including everything: ‘How much will the holiday cost, overall?’ (2) generally: ‘Overall, the weather in this area is good.’

Overall (adj.) = including everything: ‘We’re concerned about the overall effect of this film on viewers.’

Overall may be used as an adjective or adverb (NOT as a noun after in/on): ‘The examination counts for 60 percent of your overall grade.’ ‘You would have done better overall if you hadn’t spent so long on the essay question.’

Above all = most importantly: ‘Get plenty of sleep, eat properly, and above all try to relax.’ ‘The sort of person we are looking for must be well-qualified, experienced, easy to get on with, and above all able to work independently.’