Your question is not clear. But if you want to ask about casual labor, I would say that any employee engaged to meet work of a purely casual nature is a casual employee. It may include work directly connected with the core objective of the business, but in a very strict sense, the engagement of such labor to meet a business exigency shall be termed as 'temporary' employment and not casual employment.
Employees casually engaged are not employed following the recruitment policies of the company, and as such, no formal appointment order will be served to them, though all statutory benefits as mandated by the law in force will be extended to them. Normally, temporary appointment for a fixed period will be after following the HR policies with regard to such employment.
In seasonal employment, the engagement of workers during a 'season' will not fall under casual employment. They are regular employees only.
What is the significance of 60 days, I don't know. In seasonal employment, 75% attendance in each season would probably make the employee eligible for gratuity and other benefits. Therefore, it is not the number of exact days but the percentage of attendance that matters.