Not quite as invisibility since it has its own caveats, emphasis mine.

You are also adept at evading creatures that rely on darkvision. Such creatures gain no benefit when attempting to detect you in dark and dim conditions. Additionally, when the DM determines if you can hide from a creature, that creature gains no benefit from its darkvision. UA: The ranger, revised P. 8

The main difference is that, invisibility does not end when you are detected by other means that are not magical or with special senses but, in the ranger case, the condition/ability ends as soon as the ranger is detected.

The invisibility condition in PHB 191.
An invisible creature is impossible to see without the aid of magic or a special sense. For the purpose of hiding, the creature is heavily obscured. The creature’s location can be detected by any noise it makes or any tracks it leaves.

Attack rolls against the creature have disadvantage, and the creature’s attack rolls have advantage.

Now, about detection; attacking or casting a spell make you lose the benefit as stated in PHB. 195. Also, there is a big difference between dark and dim conditions (PHB. 183). The main difference is that with normal sight you can see the ranger in dim conditions but you are blinded in dark conditions. Therefore, the ranger in dim condition is not treated as if it has invisibility/heavily obscured, the ranger is treated as if in dim condition.

(PHB 195) If you are hidden—both unseen and unheard—when you make an attack, you give away your location when the attack hits or misses.

(PHB 183) A given area might be lightly or heavily obscured. In a lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight.
A heavily obscured area—such as darkness, opaque fog, or dense foliage—blocks vision entirely. A creature in a heavily obscured area effectively suffers from the blinded condition.

Thus, against the ranger when trying to detect him in dark or dim light condition, a Dark Elf and a Human are not treated differently, as if they have the same visual capacities.

As an example, by courtesy of Keithcurtis; Robbie the Ranger and Frank the Fighter are trying to sneak past Danny the Drow and Harry the Human in a dimly lit cavern. Harry has disadvantage on the opposing perception on both the sneakers, while Danny only has disadvantage against Robbie the Ranger.

In my games, a Ranger would be presumed to recognize the type of a creature who was their Favored Enemy, and I would inform them immediately of the creature type, and of their bonuses.

The only exception would be if there was a scenario where, due to some kind of disguise, or some kind of enchantment/transmutation magic, the aberration very clearly looked like something which was not an aberration. In that scenario, it would depend on particular scenario variables (does the Ranger know that aberrations might disguise themselves in this manner?), but otherwise would probably obey the same ruling.

My general interpretation of Favored Enemy is that it represents a Ranger's specific knowledge of how an enemy fights, and thus how to gain an edge against them. And with that experience/knowledge comes an intuition in identifying them. Conversely, if the Ranger doesn't know that the aberration is, in fact, an aberration—a scenario which, in my games, could occur in non-general situations—then they're not going to make the same assumptions they might otherwise make when dealing with aberrations, thus losing the bonuses.