I purchased used Beseler enlarger model 45M recently. It come with two light housings. The light from the small one on the right is greenish in colour. The other one produces warmer light. Since this is my first contact with darkroom equipment I have no clue what these are. Is one condenser and the other one diffuser? If so which is which? Which one should I use for B&W enlargement and why?

Thanks so much for your help.

SloboM.