Hello Zhuravleva!
Maybe interchangeable depending on your sentence.
"Splatter" can be noun or verb, used when you are referring to liquid that may have cause some spots on the ground or wall. Splatter are bigger splash of water/thick liquid than spatter.
Example:
"There's a lot of splatter of paint in that corner, kindly cover it up!"
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"Spatter" refers to small drops or splash or water/liquid.
-can be noun or verb
Example:
"Every time it rains, spatters is obvious on this side of the window."
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"Scatter" has a very different meaning/use in a sentence.
EX:
"Do not scatter those trash on the ground."
"Do not throw and scatter my belongings outside the dormitory when you're angry."