Japanese actually does have a ton of dialects too. Check out this map, every shaded area is a totally different dialect group:
http://www.osakaben.jp
Grammar and words can differ considerably, as well as intonation. The Ryukyu dialects, and Kagoshima are almost completely incomprehensible compared to standard! But even when comparing standard Japanese vs the kansai dialect which is relatively not that far removed, there are hundreds and hundreds of different words. There are even small differences between varieties of speech within the same dialect group. For example: Kyoto-ben and Osaka-ben are both classified as Kansai dialect, but even then there are some differences between the speech of each city. (ironically, the thing that stays exactly the same between dialects of Japanese is Sino-Japanese words).
Here's some examples:
"do not" is "shinai" in standard Japanese, but "sehen" in Kansai dialect.
"am doing" is "shiteiru" in standard Japanese, but "shitoru" in Kansai dialect.
Welcome is "oidenasutta" instead of standard "irasshaimase".
The word "desu" is "dosu" in Kyoto, and "dasu" or "da" in Osaka!
Osaka plain copula = "ya", polite copula = "da", "dasu"
Tokyo Standard plain copula = "da", polite = "desu"
The word "dakara" meaning "because" is "yasakai" in Kansai dialect.
Here's some phases for direct comparison:
言う とい たって や
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言っ ておいて あげて ね
"tell him"
yuutoi tatte ya Osaka
itteoite agete ne Tokyo
変わら へんね やった ら
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変わら な かった ら
kawara henne yatta ra Osaka
kawara na katta ra Tokyo
"if it doesn't change"
あかん ね や
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ダメ なん だ
akan ne ya O
dame nan da T
"It's no good"
ええ ね や った ら
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いい ん だ った ら
ee ne yatta ra O
iin datta ra T
"if it's okay"
えらい 風邪 もろて まんねん
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大変な 風邪を もらって いるのです
erai kaze morote mannen O
taihen na kaze wo moratte iru no desu T
"I've got a terrible cold."
はよう しとくんなはれ
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早く してください
"Please hurry and do it."
hayou shitokun nahare O
hayaku shite kudasai T
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