The U (ultra-low power) lines are indeed two-core with Hyperthreading. All others are 4 core without.
1: https://ark.intel.com/products/137977/Intel-Core-i3-8130U-Pr... 2: https://ark.intel.com/products/124969/Intel-Core-i5-8350U-Pr... 3: https://ark.intel.com/products/122589/Intel-Core-i7-8550U-Pr...