Hi,
These fields have both been deprecated, but for v201406 and earlier, they referred to the different max CPC bids you could configure for an ad group: one was the default max CPC and the other was the default content max CPC, which is the max CPC you used to be able to specify for Display Network bids. The attached screenshot is from an old ad group that had different values for these two fields. The output from the report for this ad group looks like this:
"ADGROUP_PERFORMANCE_REPORT (Jan 1, 2013-Jun 30, 2013)"
Default max. CPC,Display Network max. CPC,Impressions
500000,1250000,0
Total, --,0
See our previous
blog post regarding the deprecation of content bids for the
Display Network for details.
Cheers,
Josh, AdWords API Team