Generally,

Pu'er teas before 1940s - singular plantation
Pu'er teas between 1940 - now from some main state ran factories - blend of
maocha
Pu'er teas now from new factories - singular plantation

Blend of maocha - this can be anything from
a. leaves from different plantations
b. leaves from different regions
c. leaves from wild, part cultivated, neglected, cultivated higland,
cultivated mid-highland, cultivated sea-level plantations
d. young flush - one from spring this year, one from autumn las year
e. mix of young and old leaves
blah blah blah

Affecting factors on storing:
a. high temperature & high humidity
b. high temperature & low humidity
c. Low temperature & high humidity
d. Low temperature & low humidity
e. vacuum pack
f. natrual elements: soil, weather, etc
g. yourself, metaphysically
blah blah blah

Can you tell the leaves apart? Yes you can. Brew several samples, taste
them, and leave the leaves in a glass of water overnight. Compare the
leaves next day and document them. After a while, you can tell them apart.
I can't, I'm too lazy. I'm happy as long as there's tea to drink! :")

Can you taste the leaves apart? Yes you can. But I can't, unless I brew the
teas very strong. A friend can taste the tea and tell the difference, right
down to the blend percentage. & I'm green with envy.

ps. Mike, 6FTM has produced some of the singular plantation teas, and if
you do visit this part of the world, I'll keep some of the 16 regions for
you.

Danny