Are ICAO and FAA airport signs and markings the same?
Principle

ICAO Airport markings are defined by ICAO in Annex 14 of Chicago Convention, Aerodromes.

ICAO also requires at section 5.8 Notification of differences in the AIP of Doc 8126 Aeronautical Information Services Manual, that differences are explained in the country AIP, Section GEN 1.7 Differences from ICAO Standards, Recommended Practices and Procedures.

US regulations are not entirely compliant with ICAO SARP, and differences exist for airport marking.

Example of ICAO SARP

For the touchdown zone lights, ICAO states in Annex 14, at paragraph 5.3.13.2:


  The lateral  spacing between the innermost lights of a pair of
  barrettes shall be equal to the lateral spacing selected for the
  touchdown zone  marking. The longitudinal spacing between pairs of
  barrettes shall be either 30 m or 60 m.


US example

As US regulations are not fully compliant, the differences are explained in GEN 1.7 of the US AIP, page 129:


  U.S. does not require the lateral spacing of touchdown zone lights
  to be equal to that of touchdown zone marking when runways are less
  that 45 meters wide.


In general

All differences can be found at this location, sorted by ICAO reference and chapter. Differences related to Annex 14 start on page 124 (actually labeled GEN 1.7 81). Listing all of them (15 pages in the AIP) would be too broad for this answer.