They both seems to mean “to aim”, but dictionaries seem to indicate that it’s:
наце́лить – наце́ливать
which constitute an aspectual pair, and not
це́лить – наце́лить
as I have previously thought.
So there are a few things going on here.
In Russian verbs can contain prefixes (like
на- here) and hence change its meaning and even grammatical properties. So such verbs are not always a pair, since they are actually two different words which have the same root (
In this situation in English
нацелить и целить do mean the same thing, but the difference comes from the grammatical usage. Целить is an intransitive verb, whereas both нацелить и нацеливать are transitive verbs. An intransitive verb means that it does not allow a direct object, when transitive verbs do.
In Russian a direct object (called прямое дополнение) doesn't have any prepositions in front of it. A word which serves as a direct object is usually in the accusative or sometimes in the genitive case. Indirect objects would be constructed with a use of prepositions before a word and are conjugated in other cases.
So an intransitive verb Целить would be then:
Целить в мишень. Целить из ружья в мишень. To aim at the target. To aim a shotgun at the target.
Transitive verbs нацелить and нацеливать would be:
Нацелить ружье. Нацеливать ружье. To aim a shotgun.
нацеливать is that one is a perfective verb, whereas the second is imperfective.
Perfective verbs describe the action that happened or were supposed to happen once, the action that has already finished or it will only start. Due to the fact that the verb implies a finished action, it is never used in the present tense, it only has past and future forms.
Нацелить ружье. In English it would still mean "To aim a shotgun". The difference is more obvious in Russian when you don't use infinitive forms.
So let's consider the verbs in the past:
Он нацелил ружье. He aimed his shotgun. Action complete, he's ready to shoot.
Imperfective verb describes the action that is taking place at the current moment, actions with no indication of the start and the end, and actions that haven’t finished yet or actions are repeated multiple times. These verbs have past, present and future forms.
Он нацелиВАл ружье. He has been aiming his shotgun. Action was in progress, we don't know if he succeeded or not with aiming, we just know he's been doing it somewhere in the past.
The most sufficient difference is that целить can be used without a direct object (= целиться, метить, направлять выстрел) while нацели(ва)ть can't (only нацеливать ружьё, пистолет... на что-либо, куда-либо).
Целил в ворону, а попал в корову. (поговорка)
Вдруг вижу, что он вынул и целит пистолет (Л. Добринская)
To aim at = целиться в