Is your PDF Mapping an alternative to fillable PDF forms?

Yes - it is.
A Fillable PDF is a way to take a paper form and "bring it to life". so when a user fills it in - it is still a PDF but it is fillable. 
The goal, once the form is filled in, is for users to be able to download the document - which is now the paper form filled in with their data. 

PDF mapping is very much the same - because here you can also take a paper form, scan it and use it as the basis to create a PDF document.
and after the form is filled in generates a PDF of your paper form, containing the data that was filled in it. 
This generated PDF can then be printed by the filler, it can also be sent to him and to other recipients via email.

The main difference between the two is that FormTitan does not use a fillable PDF form to enter the data, but rather a digital form. This is because fillable PDF forms are not responsive and it's hard or even impossible to fill them in tablets and mobile devices.
What is done in FormTitan is that a digital form is created based on your paper form - as a digital version of it. and once the form is ready you just need to add a PDF Mapping to it. 
Find out exactly how to add a PDF mapping