Here are some confusing words in terms of spelling.
These also happen to be some of the common errors in pupils' English.
ALL RIGHT or ALRIGHT? - Both correct
ALL TOGETHER or ALTOGETHER - It depends...
A) There are five of us altogether. (in total)
B) The classroom has been cleaned altogether. (completely)
C) Can you put us all together in a group. (used when people/things are brought together)
EVERY DAY or EVERYDAY? - It depends...
A) I go to school every day. (each day)
B) Forgetting my bag is an everyday event for me. (daily - an adjective used to describe the noun 'event')
EVERY WHERE or EVERYWHERE? - Everywhere (One word. 'Every where' is wrong)
ANY ONE or ANYONE? - It depends...
A) You can choose from any one of these books. (means 'one of the books', usually used with the word 'of')
B) I will reward anyone who answers the question correctly. (any person)
ANY BODY or ANYBODY? - anybody (one word, means 'anyone')
*same goes to ANYTHING, ANYWHERE, ANYWAY - all one word.
ANY MORE, ANY TIME (two words, one word is considered wrong in British English)
STORY BOOK or STORYBOOK? - Storybook (one word)
MAY BE or MAYBE - It depends...
A) I may be short, but I'm taller than you. (means 'it's likely to happen', used after pronouns like I,she,he,they,etc.)
B) Maybe I'm taller than you. (means 'perhaps', used as an adverb)
C) This may be a coincidence, but maybe we should find out more before we decide what to do.