Here are the two TCL LED 4k televisions from Walmart with expanded specs. Basically very similar...look closely at the features. (If you open both links in seperate tabs can switch back and forth). The 421 has 10watt speakers vs 8watt speakers for the 435. The 421 has one less HDMI port than the the 435, and lacks an ethernet port. (wireless connection only)
Look through the specs for each and see if anything is missing that you really need that justifies the $30 price difference.