Once we visualize the two sound effects, it is fair to say they were created with different techniques.

The reason why they sound so similar might actually lie in the emotions they convey - growing up, reaching a goal... the shared ascending chords work perfectly for this purpose. 🍄

In contrast, the SMB level end fanfare sounds much more like an actual tune.

It is polyphonic, the notes do not all have the same duration, it is in 4/4, and most importantly, it has an ending (the final C chord that makes the tune "land", as if to say, "You did it!").

When slowed down, the Mushroom sound lacks a clear rhythm or time signature (it could technically be described as one 7/8 bar and two 10/8 bars).

Again, this is because its true character only comes up once we speed it up.

It's the very motion and note placement that defines the sound once we speed it up; many videogame sound effects are created with this method. Here's an example from Super Mario World.

The Mushroom sound is a monophonic, i.e., one-voice sequence (this saves on audio channels and allows it to coexist with the music). The notes all have the same duration and rise in a kind of wavering motion.

The Mushroom sound and the level end fanfare share the key and chords (C - A♭ - B♭) and are both created by arpeggiating a series of ascending notes. But this does not mean they are the same.

No problem!
(Funny anecdote, we raided you because one of Luigi's gibberish lines from Brothership sounded like the Italian for "have you seen Pikmin 3?". So we came to the conclusion that Luigi must be a Pikmin fan. youtu.be/theYBOMpOag?...)