In my country we don't have Aldi, but we have Lidl. They seem very similar, but would be interesting to learn about their differences, and what history they have in common
Though Lidl has better bakery items and more loose goods, whereas Aldi prepackages almost everything.
Originally, they had alternative ( but good) products, which really reduced your costs to shop. They almost had no brand items in the past.
They also have some goodies at a good price in the middle rows of the store.
The bakery is good too
Spar seems similar to Aldi from a consumer perspective, but is not very nice to its employees.