Loader is both RAT and Botnet simply to drop file with fud way be easily.
A malware loader is the software that drops the actual malicious content on the system/executes the first of the attack (set up).
For example, a loader may drop a *.sys file on the disk (kernel-mode device driver) and then it's start that driver which may contain malicious code for rootkit functionality, or it can download other malicious software then execute it after adding it to start-up (hence it being the loader it basically sets it all up).
HERE Loader in C#
HERE Loader in VB.net
A malware loader is the software that drops the actual malicious content on the system/executes the first of the attack (set up).
For example, a loader may drop a *.sys file on the disk (kernel-mode device driver) and then it's start that driver which may contain malicious code for rootkit functionality, or it can download other malicious software then execute it after adding it to start-up (hence it being the loader it basically sets it all up).
HERE Loader in C#
HERE Loader in VB.net