"Suillus americanus" is very similar in appearance to "Suillus sibiricus" (distributed in western North America and western and central Asia) but the latter species associates with "Pinus monticola" and "Pinus flexilis" rather than "Pinus strobus".One field guide suggests that "Suillus sibiricus" has a thicker stem than "S. americanus", brown spots on the cap, and is a darker, more dingy yellow.