The confusion about these words is that they can both be either nouns or verbs. If you ask someone, "Does 'studies' mean the same as 'researches'?" you may hear "Yes," but it is only true if they are used as verbs. As nouns, they have subtly different meanings.
"This team has done a lot of good research. I just read their latest study, which they wrote about calcium in germinating soybeans. It described several interesting experiments."
research 1. to perform a systematic investigation
1. "What kind of scientist is he? He's a botanist. He researches plants."
study 1. to perform a systematic investigation; 2. to actively learn or memorize academic material
1. "What kind of scientist is he? He's a botanist. He studies plants."
2. "Mindy studies every day. That is why she gets such excellent grades. She wants to go to college to study math."
Some authors say "research" when they mean "study." "Research," as a verb, means "to perform a study or studies," but "research" as a noun refers to the sum of many studies. "Chemical research" means the sum of all chemical studies. If you find yourself writing "a research" or "in this research," change it to "a study" or "in this study."
research The act of performing research. Also, the results of research. Note that "research" is a mass noun. It is already plural in meaning but grammatically singular. If you want to indicate more than one type, say "bodies of research" or "pieces of research," not "researches."
"Dr. Lee was a prolific scientist. She performed a great deal of research over her long career."
study A single research project or paper.
"Dr. Lee was a prolific scientist. She performed a great many studies over her long career."
The noun "study" refers to a single paper or project. You can replace "paper" with "study" in almost all cases (but not always the other way around), to the point where you can say "I wrote a study." The noun "research" means more like a whole body of research including many individual studies: The research of a field. The lifetime achievements of a scientist or research team.