Spanish Grammar Question - imperfect/preterite vs progressive

could anyone here help with some grammar rule clarification?

In my Spanish verb workbook it gives the use of the Present/Past Progressive tenses thus

‘[they] are used to express present or past (imperfect) action when that action is thought of as continuing or in progress. They are thus a more vivd, dramatic substitute for the present and imperfect, respectively.’

Can anyone give a better guideline than it being a more vivid/dramatic substitute?

can a mod edited the title of my post to imperfect/present.

In Spanish, it’s perfectly acceptable to say “I go to the store” (present tense) or “I went to the store” (imperfect) when, in English, one would say “I am going to the store” (present progressive) or “I was going to the store” (past progressive). Thus, one only uses the progressive tenses in Spanish when one wants to emphasize the continuing nature of the act. This is sometimes done to contrast the act with an event that happens during the act.

Or simply: think “used to” and you’ll get the hang of it: “Vivia en España por tres años.” - I used to live in Spain. As opposed to "going to the store, which was more of an isolated event.
Spanish is easy. Except for all the damn verbs. 14 tenses x 6, makes 84 versions.
I’m so glad for Swedish. Only three forms of every verb, for all tenses.

Here are a couple of examples for comparing, in English and Spanish. I’m not a native Spanish speaker, so forgive my mistakes if any.

Te decia de los planes ayer.
I was telling you about the plans yesterday.

Te dije de los planes ayer.
I told you about the plans yesterday.

(the distinction between the two are the same in English as in Spanish).

A cool one I learned here on the SDMB:

Yo solia manejar un Honda.
Yo manejaba un Honda.
I used to drive a Honda.

My wife says that in Mexico “soler” isn’t used very often verbally. The imperfect is preferred. Even the “solia” form is imperfect – it means “accustomed to” in the same sense as “used to” does. On that note, I think they use different words to mean “drive” in different Spanish-speaking nations as well (conducir also works in Mexico).

Compare with: Ayer maneje el Honda.

I’m not clear from any of the replies so far whether the OP is interested in the difference between preterite (manejé) and imperfect (manejaba); or whether he understands these and is enquiring about the difference between these and the past progressive or continuous form using the gerund (estaba manejando). If the last, then it is very similar in meaning to the imperfect tense, used where we would use “was -ing” in English, to describe an action that was going on (in the background, so to speak) at the time another event took place. A sentence where the verb phrase is followed by a phrase like “at that time”, or “at the time that [XYZ] happened”, or where such an idea is implied.

e.g. “La mujer, quien estaba manejando, me dijo una cosa que no puedo nunca repetir”;
“Llevaba manejando por el campo un poco más de tres horas cuando vi al hombre curioso al lado del camino.”

The use of the progressive form seems to imply longer duration than the imperfect tense.

Disclaimer: I am not a Spanish speaker; I apologise in advance for any mistakes in these examples, and will welcome any corrections.

My impression has always been that the past periphrastic progressive (“estaba (verb)iendo”) is very sparingly used, and that when stress is being laid on the continuing nature of the action: “I was always getting horny in my teens.” The imperfect is regularly used where we’d use the simple past in constructions that constitute regular and customary action: “I rode the bus to school every day for six years” – as well as the “used to” and “was doing” sorts of constructions that grammars indicate are its standard usage.