Providing ministers, HoC has whips make recommendations to the PM on suitable candidates for promotion. HoL, peers can be appointed just to be made ministers (convention). 2023, David Cameron was appointed Lord just to be foreign minister.
Passing legislation, HoC mainly creates legislation (government). HoL amends legislation, only non-financial. 2016, Cameron tried to pass legislation around trading (labour+SNP+Con defeated him).
Parliamentary Scrutiny, debating and voting- both houses. Select committees and PMQs- HoC. 2010 saw the creation of the backbench committee. Theresa Mays cabinet only contained 1 member of HoL.