Difference between Competency and skill - which applies to all levels and grades of staff in an organisation

Any employee, want to succeed in professional life, need to have three things; which applies to all levels and grades of staff in an organisation. They are ASK - Attitude, Skills and Knowledge.
Knowledge - Theororitical concepts, MOdels etc
Skills - Proficiency in a particular task or function
Attitude - How an individual behaves or receives or dispose of self in the environment arournd.
NOw COMPETENCY mean Skills + KNowledge; For example, I know what is Communication and know how to communicate effectively. It means, I am competent in Effective Communication.
SKILL mean I am good at communicating with individuals around. But here my level of skill will vary; it mean, my skilling at communication can be Novice, Intermediate, Proficient, Expert and Advanced

I think that skill refers to the ability of a person to perform a given task so as to attain a predetermined result. Skills can be improved by proper training and continuous and considerable experience. Thus skill is confined to performance i.e., what is exactly performed in a given situation as per the predetermined standard.
Competency, on the contrary, has a larger scope in that it encompasses in itself knowledge, behavior and skill and thus culminates in achievement i.e., how things are accomplished in all situations.

Competency is at Macro level but skill is at micro level.
A typist, if he is able to type error-free at a speed of 60 w.p.m (words per minute), we can call him as a skilled typist. But if his department manager /HOD can manage his department function in an effective manner, we can call him as a Competent manager.
A Surgeon's job is a skilled one, but the job of Chief Executive officer or Medical Director of that hospital is of a competent one.

do we HRs do look for skills or competencies in selecting the right candidate or matching our requirement?

In simple terms, skills are needed to be fit the requirement. experience in different areas amount to skills.

Competencies are group of skills in a common area. For example. People Management need a set of skills comes under the heading Competencies