Hello sgpu -
The maximum number of PCI lanes is 8 for either. The S1220 is not an embedded product but the C2338 is. The C2338 is part of the Intel Atom processor C2000 product family, formerly known as Rangeley. More information can be found on the Intel EDC at Intel® Atom™ Processor C2000 Product Family Overview. There is also the corporate product catalog that may be helpful to you; visit C2338 or S1220.
Have a great day! Lynn Z.