Old English (450-1100)
Sounds: more or less same as West Germanic.
Grammar: inflections with case, gender, number, etc. Word order similar to today but not fixed.
Vocabulary: more or less same as West Germanic. words borrowed from Latin and Old Norse.
Middle English (1100-1500)
Sounds: changed little from Old English.
Grammar: lost most inflections. Case not lost. Word order became fixed. Function words became more important.
Vocabulary: thousands of words borrowed from French. Borrowing from Latin continued.
Modern English (1500-today)
Sounds: all vowels shifted from those of Middle English.
Grammar: more inflections lost. Word became even more fixed.
Vocabulary: more words borrowed from French, Latin, Greek and other languages.