Neuroscience
Any or all of the sciences, such as neurochemistry and experimental psychology, which deal with the structure or function of the nervous system and brain.

Neuroscience is the study of how the nervous system develops, its structure, and what it does. Neuroscientists focus on the brain and its impact on behavior and cognitive functions. Not only is neuroscience concerned with the normal functioning of the nervous system, but also what happens to the nervous system when people have neurological, psychiatric and neurodevelopmental disorders.

Neuroscience is often referred to in the plural, as neurosciences.

Neuroscience has traditionally been classed as a subdivision of biology. These days, it is an interdisciplinary science which liaises closely with other disciplines, such as mathematics, linguistics, engineering, computer science, chemistry, philosophy, psychology, and medicine.
Georgetown University Medical Center, Department of Neuroscience | https://neuro.georgetown.edu/about-neuroscience

Cognitive Neuroscience
The study of higher cognitive functions that exist in humans, and their underlying neural bases. Cognitive neuroscience draws from linguistics, neuroscience, psychology and cognitive science. Cognitive neuroscientists can take two broad directions; behavioral/experimental or computational/modeling, the aim being to understand the nature of cognition from a neural point of view.
Georgetown University Medical Center, Department of Neuroscience | https://neuro.georgetown.edu/about-neuroscience