Change in meaning: There are some cases in which two distinct English verbs will be needed to express what can be conveyed by the use of the preterite and imperfect in Spanish. Remember that the preterite refers to the beginning or ending of an action and the imperfect refers to an ongoing condition.
Examples:
Conocí a Miguel en 1998.
I met Miguel in 1998.
Yo conocía a Miguel en 2000.
I knew Miguel in 2000.
Examples:
Conocí a Miguel en 1998.
I met Miguel in 1998.
Yo conocía a Miguel en 2000.
I knew Miguel in 2000.