Blue foam is not as durable as GG's Evazote® nor as warm for a given thickness. Although all blue foam looks much the same, its quality varies widely. Squeeze the foam between your thumb and forefinger. Inferior foam will spring back slowly, if at all. The best available blue foam has 9% EVA content. The smaller the W/m K number, the more insulating the pad is. The average thermal conductivity, for the best blue foam, is .040 W/m K, whereas GG's Evazote is, depending on the sample, .038 - .039 W/m K.
As Mike said, the two types of pads 3/8” R-value’s are similar. The best 3/8" blue foam pad's R-value is 1.35. Using Mike’s .038 W/m K for GG Evazote yields a 3/8” R-value of 1.42 for GG’s Evazote.