Normally lspci will show you just like this and would suggest they are exactly the same card:
1a:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/580] (rev e7)
1c:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/580] (rev e7)
lspci -vnn is the answer
As we can see one is a Gigabyte and the other is an MSI card. Wha........
This works with lspci and if it's outdated may not give you the exact manufacturer and device model.
For example take these 3 different RX 580's:
1a:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Device 67df (rev e7)
1b:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Device 67df (rev e7)
1d:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Device 67df (rev e7)
You ca........