In a dictionary, I saw it gives the same meaning for analyzed and analysed.
However, In some cases I saw that they used "were analyzed" and in others it was "were analysed".
Could you please help me to understand the basic difference in those words?
They both have the same meaning. "Analyse" is much more common in British English and "analyze" is the American and Canadian spelling of the same word. This is also true about these words:
analysing/analyzing
analyser/analyzer
analysed/analyzed
They all come from the noun "analysis" which is the corresponding noun in all varieties of English.
Please also note that even publishers and editors in Britain who use the "-ize" and "-ization" endings (organize, organization) instead of the (slightly) more common "-ise" and "-isation" endings (organise, organisation) still prefer "analyse," "paralyse, "catalyse" and so on for words with an -lys-.
Analyse/analyse is one of a number of words which are spelled with an -se ending in British English, and a -yze ending in American English. Both are correct, and neither is 'wrong', in American and British, but -ze is the majority usage in American English, and -se is the majority usage in British English. People in America or Britain who are unfamiliar with usage statistics sometimes insist that the minority usage in their region is 'wrong'.
