[SOLVED] What is the difference between these 2 motherboards?

[Mytic]

I'm making a list of all the parts i want for my upcoming first build , link here if interested https://uk.pcpartpicker.com/user/Mytic/saved/bPPp8d
And i was wondering what is the difference between both of these motherboards as one is r.4.0 and one is not. I have no idea what it means or what to get for my system.
R4.0 Model - https://uk.pcpartpicker.com/product...v-r40-micro-atx-am4-motherboard-b450m-hdv-r40

Normal - https://uk.pcpartpicker.com/product/LLYLrH/asrock-b450m-hdv-micro-atx-am4-motherboard-b450m-hdv

What would be a better choice and what is the actual difference between the boards?

EDIT:
Also would it be worth me spending a bit more on a motherboard if so what should i get and what difference would it make?

 

[bmockeg]

R4 is the revision of the motherboard. Best guess is it’s ready for Ryzen 3000 series. You’d have to call customer service to see. Your PSU choice is bad, quality gold Corsair is better. Intel very good nvme drive. Lowered your cas latency on RAM. Ryzen 3600 is better for gaming than 2700x. Motherboard is fine and an upgrade there probably wouldn’t benefit you.

PCPartPicker Part List: https://uk.pcpartpicker.com/list/FFXpGc

CPU: AMD Ryzen 5 3600 3.6 GHz 6-Core Processor (£172.38 @ Aria PC)
Motherboard: ASRock B450M-HDV R4.0 Micro ATX AM4 Motherboard (£53.99 @ Amazon UK)
Memory: Patriot Viper 4 Blackout 16 GB (2 x 8 GB) DDR4-3600 Memory (£77.98 @ Amazon UK)
Storage: Intel 660p Series 512 GB M.2-2280 NVME Solid State Drive (£56.10 @ CCL Computers)
Storage: Hitachi Ultrastar 7K3000 2 TB 3.5" 7200RPM Internal Hard Drive (£32.99 @ Aria PC)
Video Card: MSI Radeon RX 580 8 GB ARMOR OC Video Card (£171.97 @ CCL Computers)
Case: Cooler Master MasterBox Q300L MicroATX Mini Tower Case (£37.70 @ Amazon UK)
Power Supply: Corsair TXM Gold 550 W 80+ Gold Certified Semi-modular ATX Power Supply (£63.97 @ Amazon UK)
Total: £667.08
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-10-30 03:51 GMT+0000

 

[bniknafs9]

the one with revision 4 does not have a water pump connector on the board