Lords can only delay bills and suggest amendments, which can be overturned by the commons. In 2017 the lords attempted to add amendments onto the passing of the Article 50 Bill, to do with Eu citizen rights.
Commons has vote of no confidence option, unlike lords
MPs are more independently-minded than in the past, so less likely to toe the party line. Making commons more assertive against the government.
Commons is democratically legitimate as they have more of a right to challenge government
Committees and PMQs are used to scrutinise government- PM does not appear before the lords to be challenged
Party control is much weaker as Lords dont need to be re-elected, so the government cant rely on their own party peers backing them.
More political balance in the Lords- no one party dominates
Peers are from a range of backgrounds, so represent different groups/interests in society- legitimacy
Peers have more expertise/knowledge- this means bills are potentially more carefully and effectively scrutinised.
Government tends to dominate commons, usually having a majority, meaning bills can be passed fairly easily