Boston, MA and Barcelona, Spain have very similar latitudes (they are both a similar distance from the equator.) Why is the climate of Boston so different from the climate of Barcelona?

The climate of Boston is so different from the climate of Barcelona because regional climate does not depend only on latitude. The flow of ocean current and its temperature causes this different climates. East coast cities such as Boston have a continental climate because prevailing westerly winds continually bring them under the influence of continental air masses while westerlies bring maritime air masses and therefore a maritime climate to the coast cities such as Barcelona and others.