The difference between a grant and a tender is that a grant is a financial contribution to your activities that your entity is pursuing. Grants are normally co-funded meaning that a part of the costs will be borne by your entity and the other part by the EU. This is because the EU has a political interest in supporting such activities as it corresponds to its strategic objectives. Tenders and procurement is about buying goods and services. The EU needs to purchase a good or a service and pays the offered price. There is no co-funding.
Grants are non-profit funding opportunities that provide financial assistance toward the achievement of specific project objectives. Tenders are opportunities that allow your organization to profit from the purchase of goods, works and construction services by a public entity.
Grants and tenders from the European Union have to be requested through the Funding & Tenders Portal. The Funding & Tenders Portal of the European Commission is the central shop window for EU funding and the procurement actions for all European bodies. If you are interested in getting a grant from the EU or offering your products and services to the EU, the Funding & Tenders Portal is the main platform for that. More information here.