Hiya OP. I have never had a child in the UK system so cannot compare differences but I can tell you a bit about our education system (I'm sure someone with experience will be along shortly) I'm a kiwi (live in Dunedin)
Our school year runs from the beginning of February until about mid December (unless doing NCEA when you finish at the end of November) and then you have a 6 week summer break. There are 4 school terms here which run for roughly 10 weeks with two weeks holiday between terms.
You start on your 5th birthday here, so say if you DC started school in 2005, the majority in year 1 are going to be born in 2000 but there are going to be a few who are born from about Jan-April of 2001 who were put up a year if they were doing well and was no need for them to repeat year 1 again, so only did say 8 months of year before going into year 2. Not sure what year your DC would be, depending on when you move and her birthday etc.
Primary runs from year 1-6 but Intermediates are mine field here, some Primary schools go up to year 8, Private Schools do intakes in year 7 and year 9. Then what most children do is go to Intermediate School for years 7&8 before moving onto High School for year 9.
I would say the biggest difference is High School, Primary is fairly similar. We have NCEA (my DD is currently doing NCEA) which is our high school qualification system which you do from year 11-13. You earn credits throughout the school year doing internal assessment and exams at the end of year exams and have to gain a certain amount of credits to enter Uni, so for example DD has just earned 5 credits in Economics in Merit in an internal assessment and at the same time learning for external exams at the end of the year where she will also gain credits. We don't have bog standard ABCD here, instead you get the same amount of credits but can be endorsed in either achievement, merit or excellence and you do not receive the credits if get a not achieved.
I really hope this useful, if it helps I have barely got my own head about our Secondary school system and I have a DD in year 11. Its midnight here so I better get to bed but feel free to ask me questions :)