never been to trader joes.
but they are owned by the same company.
I think trader joes deals more in health and vegetarian type food, while aldi deals in discount food.
Trader Joe's is a neat place. In Va. they have a killer selection of inexpensive wines, strong both in reds and whites. They have some exclusive labels that apparently result from buying up surplus production (excess capacity + recession = surplus) and have bottled and can sell for around $5 a bottle.
During my recent unemployment period, Trader Joe's was a regular stop. Great value.