Turn back time to when leaves were first emerging.

Often, leaves emerge with one pigment or another dominant. It's common for other pigments, as the leaf matures and they develop in the tissue, to change the color of juvenile foliage to its mature coloration. This is something encoded in the plant's genes.

If you don't think the change is related to the aging of juvenile foliage, please rephrase the question and offer more background info.

Al

Well I have two other trees of the exact same species planted on eighter side of my house and they bothare growing much darker leaf's. My bonsai as I said before has much lighted leaf's and even some. green/gray leaf's.

Ok - now we find out you're comparing your potted tree to trees in the landscape. Is there anything else that might help us help you? One fact at a time really isn't what I meant when I asked if you could provide background information. If they are all Japanese maples, we know the species are all the same, but there are many hundreds of cultivars. Are you saying the cultivars are all the same? how do you know?

Al