To further your illustration: "i3", "i5", and "i7" is equivalent to "F150"; the model name remains the same. However, just as you look at the year of an F-150 to know more about it (a 2005 F150 is obviously a different generation from a 2015), you look at the first digit of an Intel chip after its model name to know which generation it is. So: an i3-4XXX processor is the current Broadwell, which will be replaced later this year by the i3-5XXX (Skylake, which is the 5th gen). The remaining digits further describe the processor capabilities.
Make sense?
Here's an article for further reading:
http://www.digitaltrends.com/computing/processor-product-names-decoded/