Soon I will have a contest for FOUR lines Verses and I am HOPING you will SEE and learn the differences in line layout.
Quatrian- Poetry Soup says:
A stanza or poem consisting of four lines. In the basic form, Lines 2 and 4 must rhyme while having a similar number of syllables.
Amber in the Distance
[stanza 1]
By Catie Lindsey
Violet and gray spoke of harsh rains that day, [a]
as clouds hung low in weighted accumulation, [b]*
then upon my face sprinkled Heaven's bouquet, [a]
slight at first, then swift in accumulation. [b]*
ABAB = Siliian Quatrain/Iambic Pentameter
[Ah, it's called an Alternating Quatrain! If you can do this end rhyme pattern in ten syllables per line you can write a Sicilian Sonnet!]
Below are other possible endline rhyme patterns other sites say are also Quatrains.
AAAA, AABA, ABBA, ABBB, and AAAB [EVEN 4 lines without end rhyme!]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ABBA = Memoriam stanza,/iambic tetrameter
In Memoriam
by Tennyson
Othou, new year, delaying long,
Delayest the sorrow in my blood,
That longs to burst a frozen bud
And flood a fresher throat with song.
Two of these stanzas make up the Italian Octave used in the Italian sonnet.
ABBA = Enveloped Quatrain!/iambic pentameter
"Look Before You Leap"
By Auden
The worried efforts of the busy heap, [a]
The dirt, the imprecision, and the beer [b]
Produce a few smart wisecracks every year; [b]
Laugh if you can, but you will have to leap. [a]
http://www.uni.edu/~gotera/CraftOfPoetry/quatrain.html
Okies if you print this page from the site above and keep it on your desk
BOY will you be smart! 
LAST but I am sure NOT LEAST [probably the MOST USED]
Hymnal Stanza= Iambic
Line 1 tetrameter [8 syllables perline] a
Line 2 trimeter [6 syllables per line] b
Line 3 tetrameter [8 syllables perline] c
Line 4 trimeter [6 syllables per line] b
This is COMMON MEASURE or BALLAD Measure!
Other sources seem to say any grouping of a thought
into FOUR lines is a Quatrain??
TEACHERS??? What say you? How about MUST it have meter??
Andie, Joyce, nette, David, Joann...Dee calling all smarty pants