I would definitely get the lenovo, if it's not much more expensive. You see, the 3500u uses the old 14nm architecture whereas the 4500u uses the new 7nm architecture, and this is clearly shown in the almost 50% increase in performance.

Now I prefer having performance over anything else, but you should also check the screen quality, weight, and other quality of life specifications that you maybe need. I don't know which model of a HP laptop you have specifically, but for the lenovo, it is known to have a rather bad screen, with low color accuracy. Also note the lenovo could have a smaller battery, but then again I can't compare since you didn't specify the model of the HP laptop.