A childminder's answer:
A babysitter keeps your children safe from harm in their own home and is not required to be registered with Ofsted or have any formal qualifications. A babysitter will appreciate use of your tv and/or pc or power outlet for their laptop. It is the parents responsibility to take up references and to decide what, if any, qualifications, experience or skills they want to seek when choosing a babysitter.
A childminder keeps your children safe from harm in her own home and on outings. A childminder reserves a time slot for the sole use of your child for which she plans age-appropriate activities and a nutritional menu with due regard to current regulations and advice. A childminder is required to register with ofsted, undergo first aid training and childcare courses, have appropriate insurances and adhere to or exceed the National Standards. She is required to have medical & CRB checks as are all adults living and regularly visiting her property. A childminder is a sole trader running her own business. As well as being the boss she is also the bookkeeper, toilet attendant, wardrobe mistress, curriculum planner, product buyer, maintenance & repairs technician, negotiator, risk assessor, first aider, chef, dishwasher, waitress, laundress, receptionist, secretary, interviewer, telephonist, web mistress, story teller, singer & musician, clown/entertainer, cleaner, agony aunt, nosewiper & nappy changer, publicity officer ... (nb sorry I've used feminine throughout for ease of reading, I'm well aware there are competent male childminders)