Can't readily find one that has good photos of M.alba to allow
differentiation from M.rubra - particularly with respect to bud morphology,
though I did run across some with misinformation - particularly regarding
fruit color.
Leaf morphology is usually pretty reliable - M.alba leaves are
glossy/shiny, whereas M.rubra leaves are rough/sandpapery.
In town here, M.alba is everywhere - in roadside ditches, fencelines,
cracks in the pavement, etc., but once you get out into the country,
M.rubra is more evident - mostly along roadsides and wood's edges, but also
scattered throughout the woods; nowhere is it exceptionally common, and it
would be a major stretch to classify M.rubra as 'invasive'.