They both exist on our physical plane in a static form. However they also exist consciously on higher dimensions, all beings do, although most are unaware of this simultaneous existence.
However crystals and Trees do separate on one key point:
Trees are great voyagers. They branch out across the universe/s and gain knowledge of all things - they love to travel! They love to share this knowledge with us, with source, that is why walking with trees is so inspirational. If you close your eyes and rest with tree you can share these cosmic journeys in the physical and light realms.
Crystals are stay at homes. All bunched together they love to communicate, talk and expound. They have no interest really in the physical beyond sound and colour (which they love). Crystals live as a perfect soul group, all is known. Why bother travelling when you can experience the journey through communion with light.
Trees of course can know everything and commune in the same way as crystals. Its uniquely their love of adventure and motion that sends them on their intergalactic journeys.
One day we will remember being tree and return to crystal, but for now which race do you most resonate with the cosmic adventurer or the light home bodies?
This message is manifested with light