Bit of a long one, I know. I know that they are linked in their meanings, but I don't know when to use each one. Also, there are two types of そう, such as
大雪が降りそう and 大雪が降るそう
What are the differences?
Also, I hear that みたい is almost exactly the same as よう, but is more informal. Is this correct?
I appreciate your help!
About a verbal auxiliary そうだ. 連用形(ます stem) of a verb + そうだ and stem of an adjective mean “manner“. They are close to the English word “look like“. Plain form of a verb and adjective + そうだ means “hearsay“. So 「 雨が降りそうだ」 is translated as “ It looks like rain” and 「雨が降るそうだ。」 is translated as “ I hear it will rain.” And you can omit だ.
ようだ is a verbal auxiliary which indicates "analogy" and "guess". For example, この花は、虹のように美しい(This flower is beautiful like a rainbow), 猫は家にはいないようだ(I guess my cat isn't in my house.). These are other usages. http://dictionary.goo.ne.jp/jn/226613/meaning/m0u/
だろう indicates speaker's guess. みたい indicates "analogy" and "unclear predication“. らしい indicates "“hearsay“ and "a valid guess". I think っぽい can indicate "analogy", "hearsay", “manner“ and "guess", and it isn't formal.
"大雪が降りそう" = Probably we will have big snow.(conjecture)
"大雪が降るそう" ? insufficiant. This should be "大雪が降るそうだ(hearsay)"
"みたい" is a sopken and casual word.
When you come across somebody's unreasonable attitude against you, you can say (but only on casual occasions) "馬鹿みたい" = "It's almost foolish!"
"パリのエッフェル塔みたい！", "ナイアガラの滝みたい！" and "みたい" is almost always used as "〇〇みたい."
"エッフェル塔のようだ"、"ナイアガラの滝のようだ"
We can use "滝のよう" without "だ" in the lyrics.
We don't use "みたい" in business.
We can use "ようだ、ようです" in business. "第一四半期に入って、原価が若干増大しているようだ。（ようです。）"
As A Dictionary of Basic Japanese Grammar states on page 550,
– kennysong Jan 04 '18 at 06:32The colloquial version of ようだ is みたいだ, which is also a na-type adjective. The uses of みたいだ are exactly the same as those for ようだ.