Is Arhar dal and toor dal the same thing? 
Re: Arhar dal/toor dal
I believe so...its always listed as toor dal when I go to Indian stores.
Yes it is. But it comes in two varieties - one is a dry daal and the other is “oily”. The lentil is the same and it cooks to the same flavor.
Oily
Dry
Re: Arhar dal/toor dal
How would you cook the oily one?
How would you cook the oily one?
Same as the dry arhar/toor daal. Just make sure you wash it thoroughly.
Re: Arhar dal/toor dal
The south Indian people use the oily one for sambhars I think.
Yes they are the same daal. Commonly known as toor in Punjab (India) and tuvar (in West India...like Bombay, Gujrat), and arhar in North India.
Mama made sambhar the other day out of arhar daal one of my absolute favorite dishes 
We’re originally U.P. wallay log - so arhar daal is our traditional khaana - arhar daal, chawal and aam ka achaar - YUMMY!
We’ve actually found that the oily daal is less prevalent in the markets these days - so jo bhi miljaya - either type works for us when cooking.