I wonder if there is any difference between tabs and a switcher when you have only two options to choose from. Switcher is slightly different from tabs. I think that switcher is a better solution, cause in my my example user is switching between options, switcher acts as radio buttons. Tabs are different, we're using them rather as a content switcher in the context of the whole webiste or view. Am I right, or maybe it's only result of over thinking?
1 option: switcher:
2 option: tabs:
Tabs are often misused.
Being metaphoric to real-world file tabs, tabs are content clustering controls. They shouldn't be used as a selection control (replacing buttons or checkboxes).
Just to give one example of how things can go wrong, when users switch tabs they expect the tab content to change. Often tabs used as selection controls keep the same panel content. This means users expect the panel content to change when switching tabs - but that doesn't always happen.
If I can read your wireframes alright, you are to have the same problem if using tabs.
Switchers also have an inherent usability problem in that they blend interaction with state and thus ambiguous. See Which way should be “on” for a switch? for more.
In your case, I would go with tabs, as the switcher look is not as clean, and has a little more cognitive load to make sense of it. The tabs style is the expected treatment in iOS, so go with that.
Why do they have two possible logins anyways? Just make them sign in once with one id. once they are logged in they will see the view that corresponds to the type of account they have. if they have two accounts, let them switch between them, once they are logged in with their one id. Both your options look exactly the same from an end-user perspective. Tabs usually indicate a new window/view, which you dont have here. You in essence have a choice, which is not easily conveyed in either of the options you have selected. Its not clear which choice is selected either. It maybe best to stick radio buttons in your case.
