thunderbolt usb-c same?

The general answer to whether ThunderBolt and USB-C are "the same" is "Absolutely not!"

The specific answer to whether, in the Mac implementation, you can plug a particular cable in and get it to work is, "It depends."

ThunderBolt-3 is an uncommitted computer port that can do almost anything, with the right cables/adapters. The first cable/adapter you attach specializes the port to one particular purpose, usually a more narrow subset of all it could potentially do.

To use genuine ThunderBolt devices, you must do that customization with a ThunderBolt cable/adapter. Others will not have all the wiring needed to support ThunderBolt.

The excellent counterexample: the Mac charging cable has a USB-C connector at each end. However, it is useless for most USB data, because all that it supports is Charging Voltage and( reluctantly) USB-2.

Adapters for the Thunderbolt 3 (USB-C) or USB-C port on your Mac or iPad Pro - Apple Support

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Yes. Thunderbolt 3 can be used as a USB-C port. It carries THe TB 3 signal as well as the USB-C signal.