Id expect a 14 year old to be capable of doing everything required to run a household (except family finances of course), and a 6 year old to do anything that doesnt involve very heavy, hot or sharp things (some could be done with supervision)
What about putting chores (vacuum living room / mop kitchen floor / dust tv etc) down on wee bits of paper and placing in a tub. Each child picks out say, 4 bits of paper and does them. The 6 year old would need more supervision, obviously. Add in a bit of paper with a treat written on it - "choose a family movie for friday night", or whatever.
I have index cards written out - one job to each card and a time estimate written on it. Whatever I get done while shes at school I take out, so whatevers left is to be done by us together, or in the case of ironing, by me in front of tv at night ;) )
I set a timer and challenge dd to do as many "jobs" as she can in half an hour. I do the same, then we play a game or read a story when the time is up. She also tries to beat the time est written on the card.
Yesterday she drew the card for building a bookcase (ikea flatpack) which took her almost 2 hours to complete, and I had to find more nails to replace the ones she bent....but she did a great job and was well chuffed with herself.