Hey, Benny; thanks for your post. I'll try to explain what I meant better... I think there might be some confusion, because contrabass can imply a different tuning based on whether you're approaching the idea from a classical guitar background, or from an electric bass background.
In classical guitar circles, a contrabass guitar would be tuned P4-P4-P4-M3-P4 and E-E, one octave down from a normal classical guitar (contra- means 8ve down). As I mentioned, these have been around for about 100 years. They look just like classical guitars, but are bigger, and the bottom 4 strings are tuned exactly the same as 4-string electric bass & orchestral double basses. Then, they also have a B and an E on top (both one octave down from a regular guitar).
In electric bass guitar circles, though, a contrabass usually brings up the thought of Anthony Jackson, who pioneered 6-string basses in the '70s. This could be considered a misnomer: the more correct term, from a classical standpoint, would be subcontrabass. Jackson prefers to call his instrument a contrabass guitar, instead of a 6-string bass, because he started on guitar before switching to bass, and as he was exploring the role of both instruments in music, he wanted to combine them into something he could use to cover both voices. He worked with Fodera to develop the first 6-string electric bass, which he decided to call a "contrabass," reflecting the addition of the low B string (below a bass). Anthony Jackson's Fodera is exactly the same as what other bassists simply refer to as a "six-string bass." It's a 36"-scale 6-string bass tuned B-E-A-D-G-C... nothing special tuning-wise (aside from the fact that it's a Fodera, LOL).
Now, here's the weird part... There are two completely different instruments both called bass guitars, depending on whether you're approaching it from a Niibori background, or a Fender background.
A Niibori (classical) "bass guitar" looks like a regular classical, nylon-string guitar, except that it's bigger, with a 27.5" scale length (only 2" longer than a regular classical guitar), and it's tuned a *fourth* down from a classical guitar... the same scale & tuning as what we now call a baritone guitar! It has 6 strings tuned B-E-A-D-F#-B (P4-P4-P4-M3-P4), totally different from what electric & upright bassists call a bass guitar (32-36" scale, with 4 strings tuned in fourths, E-A-D-G, or with a low B for a 5-string, or with a low B and a high C for a six-string).
Now, here's the SECOND weird part... in classical circles, a contrabass is bigger (below the classical bass). A contrabass guitar (which has been around about 100 years, in classical circles) has 6 strings, a 30" scale (approaching short-scale electric bass territory) and is tuned a whole octave below a regular guitar (i.e. the bottom 4 strings are the same as a 4-string electric bass). The reason for this is that in classical circles, contra- means pitched below the BASS instrument, not just below the prime instrument. The order goes like this:
Soprano
Alto
Tenor
Baritone
Bass
Contrabass
Subcontrabass
So, in the '70s when Anthony Jackson decided to call his instrument a contrabass guitar, even though it was tuned an 8ve + P4 below a standard guitar and had a 36" scale, it made quite a mess of the semantics involved! He used roughly the same tuning as a classical bass guitar, but an octave lower... but the name "contrabass guitar" was already taken for instruments tuned like the Fender Bass VI. To make things even worse, when Fender introduced the Bass VI in 1961, they called their instrument a Bass VI instead of the technically correct contrabass guitar, leaving the name open for Jackson ten years later!
As far as the Fender Bass VI, they come tuned E-A-D-G-B-E (P4-P4-P4-M3-P4). This, by the classical definition, is a regular contrabass guitar.
A normal baritone tuning would be a P4 or P5 up from this (A-A or B-B; still P4-P4-P4-M3-P4).
The Bass VI ships with Fender Bass VI strings gauged 0.0250.095, which are much heavier than baritone guitar strings (approx. 0.0140.068). Since it does have the same low E-A-D-G as all other Fender basses, you really could call this a
short-short scale bass guitar (30" - same as the contrabass classical guitar), with two extra strings, tuned a M3 and a P4 above that, on top. You really can't play full guitar chords on it and have it sound decent, any more than you would on a normal extended-range bass guitar.
Another big contributor to this mess was Leo Fender back in 1951 with the introduction of the Fender Precision Bass. Although he called it a "bass guitar" and marketed it as such, the tuning and longer scale-length of the instrument was borrowed from *double-bass* (because popular music of the time used that instrument for the bass voice, not the existing (classical) bass guitar (6 strings tuned B-E-A-D-F#-B [P4-P4-P4-M3-P4]).
So, really, it just depends. I don't think either answer is wrong. If the instrument has a low B string (8ve + P4 down from a regular guitar's low E-string), it could correctly be called a
subcontrabass guitar, although today we just call this a 5-string bass. (Among modern electric bassists, a subcontrabass has strings below the low B.) If a normal 5-string electric bass guitar also has a high C, we can just call this a 6-string bass (or a contrabass guitar, if you're Anthony Jackson

). If it has 6 strings but is tuned E-E like a guitar, but an octave down, it's a contrabass, or a Bass VI, if you're a Fender enthusiast, or "a 6-string bass tuned E-E," if you're most bassists
That said (whew!), I agree with you, Benny. Range, scale length, and really the most telling parttechnique employed, and simply the role of the instrument as far as playing the bassline rather than comping or playing the harmony or melody partsare what make up a bass instrument. The specific intervals between strings don't really matter, and as you said, can be changed on the fly for different songs or based on personal preference, without changing the role of the instrument's voice in context.