This is a range issue, so we turn to the Rules Compendium's entry on range:
To determine the range between a power's user and its target, count the distance between them as normal (see "Determining Distance," page 201), including 1 square that the target occupies. (RC 107)
Here's that "Determining Distance" reference:
To determine how far away one square is from another, start counting from any square adjacent to one of the squares (even one that is diagonally adjacent but around a corner), then count around blocking terrain and end up in the other square. Make sure to use the shortest path. (RC 202)
Note that it makes no mention of difficult terrain or cover, just blocking terrain. So yes, you can consider it like a burst with a single target, for the purposes of determining valid targets.
Of course, you also need line of effect:
When there is a clear line from one point to another in an encounter, there is line of effect. Unless otherwise noted, there must be line of effect between the origin square of an effect and its intended target for that target to be affected. (RC 107)