Digital Marketing functions are SEO(search engine optimization), SEM(search engine marketing), Content Marketing, campaign marketing, e-commerce marketing, SMM(social media marketing), SMO(social media optimization), E-mail marketing, display advertising, games, ASO(Apps store optimization), Bulk SMS, branding, reputation management and other digital marketing platform techniques.
If we can talk about simple SEO executive role, PPC Analyst role, SMO expert role or other single task handler then its a single activity performer. But if we hire a digital marketing engineer then its necessary that he has knowledge and working ability of all above digital marketing techniques.
Simply we can say that a digital marketing engineer is a team member of marketing team who have knowledge and apply it on web technology and digital marketing platform such as; website, apps, CRM, CMS and other software application for accomplish business marketing goals. And he need to update his knowledge time to time according to trends and technology.