A go-to-market strategy (GTM strategy) is the strategy you use to get your first customers after you launch your minimum viable product (MVP).
After you talk to your customers, you should have clear details on:
Once you have conducted market research, your GTM strategy should target the marketing channels that you have the highest confidence the channel will give you, the highest impact, for the least amount of effort.
Your go-to-market strategy (GTM strategy) is the strategy you use to get your first customers, until you have established product-market fit with your product. This may include a product launch plan, and how you will test marketing channels until you can scale up. Your marketing strategy is what you will invest more once your product is developed.
You will find similar principles apply to both your GTM strategy and your marketing strategy. However customer expectations change as you shift from targeting early-adopters to the majority of your market. Until you reach product-market fit, you will want to focus more on product development than marketing.