Is a heater Resistive or tungsten watts?

(my heater draws 1500 watt and my timer's max capacity is 1875 resistive /600 watts tungsten)

Resistive.

Tungsten refers to incandescent light bulbs.

Tungsten is an element like copper... Wikipedia is good read...
Some heaters are made with tungsten although the ones I've seen were more industrial than residential...
The only sure answer to dx4530's question is to read the manufacturer's listing information.