The differences between social media marketing and digital marketing are elaborated in the following points:
Social Media marketing is a type of marketing that uses social media sites, to boost the traffic and increase customer engagement.
On the other hand, digital marketing refers to the modern marketing technique, which uses all available and cost-effective electronic channels to promote products or services and increase customer reach.
In social media marketing, the reach is limited to the boundaries of the social media sites and so does the internet. Conversely, digital marketing does not rely only on Internet-based platforms, as it can also be performed offline and so, the reach is comparatively wider.
In social media marketing, content is regarded as the king and so the better the content is, the more will be the customer engagement. On the other hand, in digital marketing focuses on the banners, to create an impression on the minds of the customer.
In social media marketing, the marketer aims at actively engaging with the social media user. Conversely, digital marketing stresses on reaching the target audience using different channels such as TV, radio, mobile apps, email ads, search ads and so forth.
If you compare the speed of a product advertised on social media and digital media, then obviously social media will win as the reach is faster. This is due to an active response of the user, in the form of like, share, comments and statuses, which helps in reaching a larger audience in seconds and so digital media is slower.