While sales promotion and sales activity are both aimed at selling more goods or services, they are not the same thing. Sales promotion is more direct inducement that is meant to get a customer to buy in the near term. By contrast, sales activity can also encompass activities that are meant to build relationships and to result in more sales in the longer term.
Sales promotions are all about the short term. These are activities that make it more likely that the consumer will buy right now. For example, a car dealer might invite people to come and test drive a certain car with no strings attached. They would hope that this would lead people to buy the car after having driven it. Another sales promotion activity would be a point of sale display. This puts the product in front of the buyer and makes it more likely that they will notice it and buy it. These sorts of activities are aimed at inducing an immediate sale.
By contrast, sales activity can be more focused on building goodwill between the seller and the customer (or potential customer). The salesperson wants to make sure that the consumer is thinking of them and will therefore be likely to buy from them in the future. For example, the salesperson might call the customer just to talk. The salesperson wants the customer to spend time with them so that the customer will be more likely to buy in the future. This is a much less direct inducement than a sales promotion is.
Thus, sales activities include more than just sales promotion. They also include activities that are not directly aimed at making an immediate sale.