If the desired package cannot be loaded, then the library() function gives an error message and display while the required () function is used inside the function and throws a warning message whenever a particular package is not found.

In R, both the library() and require() functions are used to load and attach packages, but there is a subtle difference between them:

library() function:

The library() function is used to load and attach packages to your R session.
If the specified package is not installed, library() will try to install it before loading. If installation fails, an error will be thrown.
If the package is already loaded, library() will not reinstall it.
Example:
library(ggplot2) # Load and attach the ggplot2 package
require() function:

The require() function is also used to load and attach packages.
If the specified package is not installed, require() will try to install it before loading. If installation fails, it will return FALSE without throwing an error.
If the package is already loaded, require() will not reinstall it.

Example:
if(!require(ggplot2)) install.packages(“ggplot2”) # Load and attach ggplot2, install if not installed
In summary, the key difference is in how they handle package loading failures. library() will throw an error if the package cannot be loaded, while require() returns a logical value (TRUE if successful, FALSE otherwise) without throwing an error. Depending on your use case, you might prefer one over the other.