All drugs have 2 or more names. The generic name is Ibuprofen,which is the "chemical" name ,if you like of the components of the drug.
When a drug company wants to market the drug they give it their own name ie "Nurofen".
It is the same drug but in a different box,and a different price.
What you have to watch is some manufacturers like to "sell" their product with "marketing techniques" such as a nicer colour and a nicer taste than their competetiters(sp?)hence "additives",which can make your child go "loopy",or they may be sensitive to.
I was always advised,by a Pharmacist friend,to avoid Calpol as it has colours added.
The generic named drug is always cheaper too.
So Paracetamol Syrup is cheaper than Calpol,and shouldn't have the additives.Ibuprofen syrup will be cheaper than Nurofen syrup.No difference in the "pain-killing" aspects of it though.
As previously stated, when a pain is an "inflammatory pain" such as Toothache,period pain,Sprains,etc.Ibuprofen is a drug of choice,but paracetamol is good as a general painkiller.
You can give them both at the same time,if necessary.But at least staggering them,you have a "back-up" if things arent getting better.
With my DD1 when she had temps of 40 degrees,Ibuprofen was the only thing that would touch it.HTH