The Dutch found/stole the way to the East Indies from the Portuguese. A lot of sailors went from modern day Netherlands to the East Indies to acquire expensive spices. These expeditions were paid through coorporations. Ordinary people could chip in some money which would then be used to outfit a ship and crew for the voyage east. When the crew completed its journey it sold its goods and the people received their dividends.

Competition was killing and the Dutch were beating themselves in their own game. Many coastal cities started their own coorporations and soon the price of the spices dropped dramatically because so many voyages were send out east.

Seeing their profits diminish the Dutch gave the Vereenigde Oostindische Compagnie (translated: United East Indies Company) a monopoly on the voyages to the East.

In order to protect this monopoly the VoC was allowed to have its own armies, declare its own wars and administer its own lands. It was essentially a state within a state and a very powerful one at that.

The West India Compagnie didnt get these powers. They weren't allowed to declare their own wars, administer territory etc. Instead this company was mainly focused on piracy. The Spanish were at war with the Dutch and hauled back lots of valuable goods (mainly gold and sugar) from their colonies. The main (founding) goal of the West Indies Company was distracting the Spanish from the war in Europe by harassing them at sea in the West.

TLDR: The VoC was mainly driven by profit with its main goal being profits. Being quite ruthless to achieve such profits.

The WiC was mainly founded to undermine Spanish war effort.