The rp vowel /o/ can also be replaced by a long vowel /o:/:

RP long [loη], forest [forist], sorry [sori]

GA long [lo:η], forest [fo:rist], sorry [so:ri]

4. As GA is not as strictly codified as RP, there is considerable variability in GA vowels in the open back area. Fewer and fewer Americans distinguish the vowel of lot [la:t] from that thought [o:]. This feature is called cot/caught merger and is most spread in the West (70% of the lexicon). (according to The phonological Atlas of North America, completed by William Labov at the University of Pennsylvania).

5. American linguists do not use the terms long and short vowels. Experimental data showed that in reading pairs of words with contrasting historically long (tense) and historical­ly short (lax) vowels RP speakers demonstrated, on the average, the ratio of 1.5:1, while with GA speakers the ratio is only 1.2:1. In certain contexts the contrast disappeared altogether.

6. The American /ae/ vowel is somewhat closer than the RP /ae/ so the phrase Merry Mary married sounds as if all the accented vowels are identical. Besides, in GA /ae/ is used not only in the same words as in RP but also in many words in which RP has /a:/,

e.g. RP dance [da:ns], ask [a:sk], pass [pa:s];

GA dance [daens], ask [aesk], pass [paes].

In phonology it is called a difference in distribution of the phoneme.

The diphthong [әu] is more rounded in GA:

RP go [gәu], home [hәum];

GA go [gou], home [houm]