While you wait for a fresh and specific answer, you may be interested in these two recent answers to related questions.

1. /u/jbdyer explains the relative dearth of USian government space propaganda posters in terms of the two programs' respective level of militarization.
2. /u/mikitacurve describes how the Soviet space program was more limited by its relationship to ballistic missile development than the US program.

The partial severing of the space program from weapons development, and the associated partial declassification of the program, was a luxury the USSR could not afford. The US could, and it offered political and propaganda advantages.

EDIT: Added missing links.