I believe you should do both. From my understanding, the SOP is for you to answer questions like your reason for applying to this school, program, and etc. Also, it will he used for consideration for financial support.
The personal statement is there for you to explain in depth the struggles and any important experiences you faced in life . Also, it will be used for consideration for the fellowships listed on that page.
And on each page, it’s has questions that can help guide you. You don’t have to answer all of them but you can touch on one or two questions that are most important to you.
Read the bullet points under the promps. cnsmith is correct. The first one, the SoP is what most schools ask for, the second is a little more specific to UCLA (though USC has a similar question). The Personal Statement is more interested in what adversity you have overcome and how you can contribute to your academic and professional environments.