Are ‘landrace’ and ‘heritage’ one and the same?

Almost. Landraces go further back, to the beginning of domestication. They are half-wild, half-domesticated and still genetically variable, as they continue to evolve.

Landraces have been maintained by farmers rather than breeders or researchers. 

Heirlooms/ Heritage varieties are much younger, by definition. They are often descendents of landraces. 

Why are landraces so important?

Landraces have naturally adapted to a certain place, and ecosystem over a long period of time. Because of this, they are more resilient and purposeful than modern varieties. They stand strong, organically, because they have had time to develop survival mechanisms, to cross naturally and to evolve parallel to cultural needs. 

How do landraces spread?

They follow farmer migrations. Imagine their historical importance?

What are some of the superpowers of a landrace?

Overall intelligence. Deeper roots to stabilize the plant, for ultimate water scavenging, and effective nutrient uptake. Wider leaves for photosynthesis, leading to higher digestibility. Height, to tower over weeds.