Are thunderbolt 3 motherboard act the same as laptop?

[Evister]

I currently have an idea to build a Mini-ITX Desktop (or smaller) that can be used as laptop-like desktop.

So thunderbolt 3 seem to be the solution for me to build a laptop-like desktop that is light weight and can be moved around the house when I want to surfing an internet.

Could thunderbolt 3 motherboard connected to eGPU as same as laptop?

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This is my build plan

without eGPU: I want to use it for surfing an internet or an office working and I want it to be portable.

with eGPU: I want to connect to an External GPU using Thunderbolt 3 motherboard when I feel like to gaming 

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CPU: Intel Core i7 - 6700 

Motherboard : https://www.asus.com/Motherboards/Z170-PREMIUM/ or something that supported thunderbolt 3 ( http://www.tomshardware.com/news/gigabyte-ga-z170x-thunderbolt3-firmare-update,30438.html )

Ram: DDR4 16GB (8GBx2) for VM

HDD: m.2 SSD and 7200 rpm HDD 2.5"

Monitor: GeChic 1303H 13.3" USB Powered Monitor

PSU: Seasonic S12II 620Watt

Graphics Cards: Integrated GPU

External GPU: GeForce GTX 980 Ti

External GPU chassis: BizonBOX 2 or something better

Case: Mini ITX case fanless (still finding)

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Why I want to use thunderbolt 3 instead of PCIe x16?

Because I want to move the case with motherboard + USB Powered Monitor around the house and use wireless mouse+keyboard combo.