PIP pays a portion of your own medical bills and lost income after a crash, no matter who caused it. Texas law requires auto insurers to include PIP in a policy unless the policyholder rejects it in writing, and the minimum limit is $2,500 (Texas Insurance Code § 1952.152(a), § 1952.153(a)). Because PIP is no-fault, you do not have to prove the uninsured driver caused the crash to use it.
Medical payments coverage, often called MedPay, is a separate optional coverage that pays medical expenses for you and your passengers after a crash, also regardless of fault. Policy language determines who and what MedPay covers. Both coverages can pay early medical bills while a UM/UIM claim or lawsuit is still pending.