Start with checking the active ingredients list, should be "pinus maritima" and the concentration. Im my own casual research pine bark is rarely Pinus Maritima"...other compounds pass as pine bark but are not the original compound.
This is the most affordable I've found, though Pine Bark Pinus Maritima has not had a detectable effect for me: http://www.amazon.com/gp/product/B0...UE4X&qid=1458215889&ref_=sr_rp_1_a_it&sr=sr-1
Pycnogenol is a trademarked name of Horphag Research of its patent process extract of Pinus pinaster species of maritime bark (cit. Berkeley Wellness) flourishing in southwest France.
Livestrong citing Sloan-Kettering states that their is "little or no difference" between French maritime bark extract and Pycogenol. They note the species source as Pinus maritima.
The product in the blue bottle sold by Vitamins Because is labeled as "French Maritime Pine bark ( Pinus maritima )150 mg of 90% total polyphenols."
The Pycnogenol site claims that its bark is sourced from "French maritime pine trees grown exclusively in Les Landes de Gascogne forest in southwest France. The forest is unspoiled and natural, with no pesticides, no herbicides." Examine.com says it is standardized by weight to 65-75% procyanadin compounds.
The active ingredients in both are often cited as a OPC's ,also called procyanidolic oligomers (PCOs).
A majority of users claim to get the same benefit from the V-B product. It could be that differences in the extraction process favor different ratios of compounds.