When referring to the waste matter (toileting) of animals you can use the term 'Poop','excrement' or 'droppings'
Poop is more of an informal term and excrement is used more as it is a politer way of saying it
Droppings are usually referring to a small animal like a hamster/guinea pig etc as they are alot smaller
Although these all mean the same thing, they would be used in different places.
Faeces / excrement / stools are formal language that you might use if you were speaking in medical terms
'I'd like to collect a stool sample for testing''
Poo / Poop are quite slang, but polite slang that it would be OK to use in most company. These words could use used in relation to animals or to people.
'I just trod in some dog poo, it stinks!''
Droppings / Manure would be used exclusively about animals. Droppings would tend to be used when talking about animals like rabbits or mice. Manure would tend to be used for large animals like horses.
'We must have mice in the shed. I found their droppings'
'My neighbour says I can collect some horse manure for using in the vegetable garden''
これらはどれも同じ意味ですが、異なる場面で使われます。"faeces"と"excrement"、"stools"は、医学用語としても使われるフォーマルな単語です。
'I'd like to collect a stool sample for testing'
（検査のために便を採取させてください）
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"poo"と"poop"はかなりスラング的です。ただ、丁寧なスラングなので、ほとんどの場面で使えます。
'I just trod in some dog poo, it stinks!'
（犬のふんを踏んじゃった。クサい！）
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"droppings"と"manure"は、動物についてのみ使われます。"droppings"はうさぎやネズミなどのふんについて使われることが多いです。"manure"は馬など大きな動物について使われることが多いです。
'We must have mice in the shed. I found their droppings'
（小屋の中にネズミがいると思うよ。ふんがあった）
'My neighbour says I can collect some horse manure for using in the vegetable garden'
（近所に野菜の肥料に馬のふんをくれる人がいます）
"Feces" or "fecal matter" is the more scientific term for solid waste excrement if you are speaking to professionals. Of course this could be mixed with liquid waste also and therefore excrement is more general; feces more specific to solid waste.
That said, there are hundreds of slang terms for excrement in English and vary by region. One such example that is less vulgar and somewhat innocent/polite and understood broadly in the English speaking world would be "doo doo" ("dog doo doo").
There is also a really good emoji for this that is understood universally :)
This is a tricky one as it may come across as vulgar and coarse, so I would stay away from words like “crap” or “shit”, which also double up as swear words in English, and go for less offensive terms such as “poo”, “poop” or “doggy doo”. For example, “the irresponsible dog owner let her pet do a poop in the street” or “the responsible dog owner used a poop bag to clear up the doggy doo”.
これは下品になることもあるので、ちょっと気を付けなくてはいけないですね。
“crap”や“shit”などの言葉は避けて、より柔らかい“poo”や“poop”、“doggy doo”などを使うのがいいでしょう。“crap”や“shit”は“swear words”（ののしりの言葉）でもあります。
例えば：
“the irresponsible dog owner let her pet do a poop in the street”
［訳」無責任な飼い主が、犬に道でふんをさせました
“the responsible dog owner used a poop bag to clear up the doggy doo”
［訳］犬の飼い主は、ふんを袋に入れて持ち帰りました
Fecal Matter
This is one of the many formal ways of describing it. You want to use this phrasse when you are talking with someone formally or doing a presentation. This phrase covers all types of fecal matter from humans to animals.
Poop/Doo doo
These words are informal and mainly are used by children to let their parents know they need to go to the bathroom. We are taught this at a very young age so as we grow older it sticks with us. It is also a humorous way of talking about fecal matter or a way of not being so graphic about it.
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