cURL is the name of the project which depicts: 'Client for URLs' and also be called as Client URL Request Library
it combines two separate packages: curl and libcurl.
curl is a command line tool used to get documents/files from or send documents to a server, using any of the supported protocols: DICT, FILE, FTP, FTPS, Gopher, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMTP, SMTPS, Telnet and TFTP.
libcurl is the underlying library curl uses to do the actual networking and transfer work. libcurl is used by thousands of services, applications and devices and very often through one of the "language bindings" that allows programmers of higher level languages to access its powers.