Is it common to layout sprinkler heads differently between front and back yards?
Yes, it is.

Water needs of your yard and landscaping will depend on several factors: 


type of grass / plant / tree
different types of plant in the same area
amount of sun / shade the area gets


Based on number 3 alone, back yards tend to get differing amounts of sun / shade than the front yards due to the house itself, and so that may lead to a different layout. It could be that only the part of the yard nearest the house needs to be laid out differently, or maybe just one side of the yard.

Just as important as where the sprinkler heads are laid out, though, is how they are connected. This is done with "zones" - groups of sprinkler heads all connected to the same valve, so they all run at the same time and for the same amount of time. Some areas of your landscaping require more water than others, and so it's important for those areas to be in a different zone. This allows you to water those zones for longer, giving the areas which need more water more water while not drowning those areas that don't.

On top of all of that, the maximum number of sprinkler heads is determined by the incoming water pressure, as well as the flow rate of all the heads. You can't have too many in one zone or they won't put out the correct amount of water.

Shaded areas should probably be in a different zone than sunny areas, so the sunny areas can get watered for longer. Additionally, your plants which require lots of water should be in different zones than those which require little water. And none of the zones should have too many heads.

All that could lead to a lot of zones (they make controllers with 8, 12, or 16 zones, and some installations require multiple controllers!), which could also mean a lot of trenching and PVC installed. You and your landscaping contractor will probably need to balance the "ideal sprinkler layout" with the cost and effort involved in getting it.