Trezor T creates 12 word seed phrases by default, while the Trezor One creates 24 word seed phrases by default. However, by using the command line interface you can generate a 12 or 24 word seed phrase (or a 18 word seed phrase) with either device. You can also restore seed phrases of 12, 18, or 24 words to both devices, so your plan of restoring your 24 word seed phrase from your Trezor One to your new Trezor T is entirely possible.