Portable internet access and mobile internet access are two things that actually sound like they are the same thing, but they actually have some things that are different. If you ever use the internet, you probably use some sort of access that you have installed in your residence. If you use a portable internet access, this refers to the internet access that you do not need a router or plug your computer into anything.
Instead you probably use Wi-Fi. However, mobile internet access refers to using your mobile device for the internet using either your data plan to have access to the internet or you can use wi-fi that is on your electronic device. For either one, you can use a wi-fi hotspot in a local café.