Question: Is there a difference between discipline and hard stuff designed 2 strengthen us?
Answer:

Hebrews 12:3-11 says that God corrects or disciplines those who are his children, those whom He loves, for their good (Heb 12:6, 10). His purpose is to bring about greater purity of character. This discipline then is good, in that it produces “the peaceable fruit of righteousness” (Heb 12:11).
In the classic passage on believers experiencing trials or tests , James 1:2-4 says:
Count it all joy my brethren when you encounter various trials, knowing that the testing of your faith produces endurance. And let endurance have its perfect result, so that you may be complete lacking in nothing”
Both discipline and trials produce something good!…”the peaceable fruit of righteousness” and “endurance.” They both produce good fruit: righteousness, endurance and joy! They both result in greater communion with God and a deeper trust in His faithfulness.
In the end, both of these things – discipline and trials – are designed by God to produce greater stability, godliness and righteousness in our lives as believers!
They are two sides of the same coin! God’s discipline and our trials both reflect His desire to display His great love and transform us into the image of Christ! And that, ultimately, brings great glory to His name and lasting good into our lives!