In "A Modest Proposal," Swift tries to be (and succeeds at being) shocking and outrageous in his suggestions and statements. For instance, he suggests that there are individuals in Ireland that would be properly used for food. I hope my answer has come to your help. God bless and have a nice day ahead!
"The R-pe of the Lock" is an example of a Horatian satire. The purpose of Horatian satires is mostly to entertain and mock in a funny way. It focuses on the peculiarities of human behaviour, particularly when these seem nonsensical. It has not desire to provide social criticism or to motivate social change.
On the other hand, "A Modest Proposal" is an example of Juvenalian satire. This type of writing can also be humorous, however, its main objective is to criticize society. It is mostly led by indignation or outrage at a particular injustice. In the case of Swift, the injustice was the treatment of poor Irish people.