Block deal is a trade, with a minimum quantity of 5,00,000 shares or minimum value of Rs. 5 crores, executed through a single transaction, on the special “Block Deal window”.
Bulk deal is a trade, where total quantity bought or sold is more than 0.5% of the number of equity shares of the company.
The orders in a block deal are not shown to the people who trade from normal trade window. Bulk orders, on the other hand, are visible to everyone.