What is the difference between "this_region" and "provinces_in_this_region"?

[Scorpius_Brutii]

topic

[Tsarsies]

this_region = the effects only affect that particular region.
provinces_in_this_region (i assume you meant "regions_in_this_province") = the effects affect all regions in that province.

for example. Say a building grants a growth bonus. this_region would only grant the bonus to that region. Whereas regions_in_this_province will grant the growth bonus to all regions in that province.