I'm going to build a pc late at this month with AMD ryzen 7 3700x and rtx 2070 super and i have a tight budget for other components.......still i can consider more if its actually worth (thanks for advance)
Of course there's a difference... usually in VRM quality/phase counts, extra heatsinking, Intel Lan, WiFi, overclocking features like on-board power button, dual BIOS switch, trouble code displays (not just LED's), etc.
As others have said, there are many decent B450 board that are literally hundred's of dollars cheaper and can be used quite nicely. Stretch for the GPU and save where you can elsewhere.