Bare Infinitives

I had always thought that bare infinitive and base form were the same until I discovered that some scholars affirm they’re not the same. To tell the truth I haven’t understood what the difference is. Modals are followed by a bare infinitive or the base form? What about Let and  make? And verbs of sensation ? May be it’s a trivial question and I’m being fastidious but… Thank you!  Carla 

In terms of meaning, the bare infinitive (without “to”) and the base form (with “to”) are pretty much the same, but the modal verbs (“should, would” etc.) take the infinitive without “to.”
The infinitive is a strange thing in English. Basically, you shouldn’t “split” it, i.e. put an adverb between “to” and the verb, but this is now acceptable. The most famous example comes from Star Trek: “to boldly go where no man has gone before.”
And, seeing as you like language points, we can tell you that “fastidious” is rarely used in English: “fastidioso” is usually translated as “irritating, troublesome, annoying.”