Here AmE uses “connection”, “reflection”, thus following the principle of derivational unity: connect > connection, connective; reflect > reflection, reflective.
Regularization
This principle is employed more completely in AmE than in BrE. It shows up most obviously in the regularization of the endings -or/-our to the single form -or.
There are no systematic criteria for distinguishing between the two sets in BrE:
BrE BrE
neighbour but donor
professor
honour but metaphor
savour but manor /'mæn ə /
flavour
behaviour but anchor
colour
In BrE the suffixes –ation and –ious usually lead to a form with –or: coloration, laborious, but suffixes –al and –ful as in behavioural and colourful have no such effect. However, AmE may keep –our in such words as glamour (next to glamor) and Saviour (next to Savior).
But in such words as contour
tour -our is never simplified.
amour
AmE mold BrE mould
mustache moustache
molt moult
The second well-known case concerns –er and –re. British words in -re are regularized to -er in AmE. E.g.: BrE centre AmE center (but central)
metre meter
This rule applies everywhere in AmE except where the letter preceding the ending is c or g. In these cases -re is retained: acre /'eikə /
mediocre
ogre /'eugə/
Derivational Uniformity
BrE writes defence AmE has -s > defense > defensive
offence -s > offense > offensive
pretence -s > pretense > pretension
but to practise (v) but to practice (v) > practical
In another case BrE observes this principle and AmE violates it:
BrE analyse AmE analyze
paralyse paralyze
And their derivation cognates in BrE are “analysis”, “paralysis”.
Reflection of Pronunciation
This principle has been widely adopted in spelling in both varieties for verbs ending in -ize and the corresponding nouns ending in -ization. The older spellings with -ise and -isation are, however, also found in both AmE and BrE (in publishing style – preference for z). However, some words such as
to advertise
to advise
to compromise appear only with –ise
to revise
to televise
In AmE “l” is doubled if the final syllable of the root carries the stress and is spelled with a single letter vowel e/o. If the stress does not lie on the final syllable “l” is not doubled
to re'bel - re'belling but 'travel - 'traveler
com'pel - com'pelling 'marvel - 'marveling
con'trol - con'trolling ' revel - ' reveling
pa'trol - pa'troller ' yodel - ' yodeled
Hence AmE spelling closely reflects pronunciation. The AmE spelling fulfill, distill may be favoured over simplified Br fulfil, distil because they indicate end stress. BrE, in contrast, follows the principle of regularization since all final “l’s” regardless of stress are doubled (e.g. traveller, marvelling). In a few cases BrE doubles the final “p” where AmE does not, e.g. kidnap(p)er, worship(p)er.
Perhaps the best-known cases of spellings adapted to reflect pronunciation are those involving -gh-. Here AmE tends to use a “phonetic” spelling so that
BrE plough turns into AmE plow
draught draft
(a flow of air)
AmE thru (BrE through) and AmE tho (BrE though) are not uncommon in AmE but restricted to more informal writing and sometimes show up in official use.
Such spellings as AmE lite, hi, nite (BrE light, high, night) are employed in very informal writing and in advertising language.