Enemies are Opponents and vice versa
The sentences in question are using enemies and opponents interchangeably, and in general, the book treats the two words like this.
She rolls (Perception + Occult) as an undodgeable decisive attack applied in a line against enemies out to medium range. This line is wide enough to strike all opponents within the width of a single range band and reaches high enough to strike aerial enemies who are at short range to the ground (medium range enemies in the air can still be targeted by directing the butterflies to fly along an upward path, rather than a horizontal one). Battle groups are especially vulnerable to being cut down by this spell, taking a -2 penalty to Defense against it.1
Neither Enemies nor Opponents are ever explicitly defined in the rules, though the box Noncombatants and Trivial Opponents distinguishes those two types from any other opponent or enemy.2 Most notably, keep in mind this one sentence from the box:
though, [attacking bystanders] shouldn’t be necessary — bystanders
are mostly there to provide stunt opportunities for the
players’ characters and their opponents.2
In general, the book seems to contain two styles for paragraphs or rules snippets, depending on the preference of the writer of a mechanic for either enemies or opponents. In total, the core book use 687 times Enemy or its plural (370 + 314), and 387 times Opponent and its plural.
In the absence of a specific definition in the book, opponent and enemy have their ordinary, trivial meanings as you would find them in a dictionary. As such, it seems best to treat the two words to both mean the same.
Here things get a tiny bit tricky: on the literal reading, the abilities in question do not target non-enemies or non-opponents. On the other hand, they don't actively disclaim collateral damage.
But in Exalted, this is a chance for you to actively describe such as part of a stunt! In fact, the box I called out above actively encourages you to stunt using the bystanders to make your action more awesome. Let's take two approaches to use Death of the Obsidian Butterflies on some enemy pursuing down a road with people.
Example One: spare bystanders
Player: Blooming Red Shadow concentrates hard, stretches out the arm, and materializes their essence in a cone of black volcanic glass shards. The literal Death of the Obsidian Butterflies is sent down the road, into the group of monks that try to apprehend the solar. But in their glorious benevolence, they nudge those slivers forming between the palms with the fingers in just the right way that the bystanders are narrowly avoided and only the monks pay a bloody toll for assaulting.
GM: Ok, I think that qualifies as a 2-point stunt. Roll for it.
Example Two: No One Spared
Player: Red Clouds Rising laughs as they stop in the middle of the road, facing the crowd that the Dragon-Blood is forcing themselves through. Opening their right palm towards the brass-clad hulk, a purple-black wisps condense into a black hole that seems to open into the void beyond space. Behind, the furnace of creation roars, fire turns to earth and a couple of sparks escape through the hole ripped into Creation. Condensing into sharp, jagged things, slivers of Obsidian, shaped like malformed butterflies, flow down the road in a deadly swirl, cutting the commoners in the way of the Imperial Dragon-Blood just as much as him and creating the literal red mist for which they were named...
GM: Ok. One point stunt and the road turns into difficult terrain for movement, but no longer cover. You just mow down his cover after all.
1 - Exalted 3, p.472.
2 - Exalted 3, p.208.