With my children moving up to Year 1 was very different. This is how I found it different but some schools may be better at merging the years together for a smoother transition. My childrens school it was very much a case of Reception = play, year 1 = work.
In Recpetion they had been allowed to sit where they wanted, to play with whatever they wanted when they wanted. Things like the painting was always set up and used constantly through the day and learning was very much via play.
In year 1 this all changed. They had to sit at specific tables and they had a more structured day where Maths/Writing/Art etc would have a specific time slot. The teacher would 'teach' them in a more orderly manner with less play and the subjects are taught seperately as individual lessons. They would have homework which had to be completed and would be displayed on the wall. This was also the way the children could boost their 'team points'. They have charts on the walls where their progress is mapped which my son loved when he got moved up.
They should start to write short stories and write about and recount events (like school holidays). They should learn addition and subtraction, division and multiplication usually in simple terms they understand like dividing a cake into 4 pieces etc . They start more independent working too where they may be asked to work on their own to produce a piece of work or in pairs/groups to solve a specific maths / science problem.
PE is provided on a regular day every week where before it was a case of taking their PE kit in on a monday and leave it there all week as it would be used randomly.
It is structured more like the rest of the school with orderly lessons and discipline is firmer too because they are expected to understand consequences. It is going into year 1 I found the hardest for my son because he really enjoyed playing and he really disliked work. He isnt any different now, he finds school work boring and very difficult. Its just not of any interest to him whereas my daughter thrives on achievement, she loves getting team points and awards and she really enjoys the more difficult tasks.
BBC have some brilliant school curriculum information. Year 1 is the start of KS1 so have a look at the sort of things they will be doing.