The terminology makes no difference. Essentially the difference in the degree of efficiency.

To add to the previous answer with which I totally agree

efficiency is the ability to obtain the maximum possible benefit, given the resources available.

effectiveness is the benefit of using a technology, programme or intervention to address a specific problem under general or routine conditions, rather than under controlled conditions, for example, by a physician in a hospital or by a patient at home. 

efficacy is the benefit of using a technology, programme or intervention to treat a particular problem under ideal conditions.

In regard to that when for CEA data from RCT are used we have to bear in mind that in fact this is a cost efficacy rather than cost effectiveness analysis.