Dynamics 365 Business Central and Dynamics 365 CRM are two separate products that must be purchased individually. While they may seem to have similar capabilities in some areas, each excels in the particular purpose for which it was designed.
Dynamics 365 Business Central’s Relationship Management capabilities may satisfy some companies’ lead management needs. Its basic sales management features include:
• Manage contacts
• Manage opportunities
• Manage quotes
• Campaigns and segments
Business Central allows you to enter prospects, turn prospects into customers, enter quotes, and turn quotes into orders for completion using the software’s supply chain capabilities.
For businesses looking for a full-fledged sales and marketing-focused CRM solution, though, that may not be enough.
Dynamics 365 CRM makes a better choice for sales and customer management when companies…
• Need a deeper Outlook integration
• Have complex business processes that require workflows beyond what is available in Business Central (e.g., lead distribution to sales representatives, by territory, etc.)
• Want enhanced marketing automation, customer service, field service, etc.
• Want mobile access to all CRM features
Fortunately, Dynamics 365 Business Central and Dynamics 365 CRM have a pre-built integration, so Business Central customers can get the ERP functionality they need, plus the full spectrum of sales and customer management features in Dynamics 365 CRM.
For example, the Business Central – Dynamics 365 CRM integration allows you to accomplish a complete quote-to-cash process:
1. Enter quotes into Dynamics 365 CRM using the price lists from Business Central.
2. Convert quotes into orders, with the ability to see Business Central’s inventory availability in Dynamics 365 CRM.
3. Ship and invoice orders through Business Central.
4. Receive and post cash against invoices from within Business Central.
5. See the payment status of invoices from within Dynamics 365 CRM.
For Business Central customers with full CRM needs, the integration offers the best of both worlds.
• A common login experience, managed through a single Dynamics 365 account
• An out-of-the-box integration, requiring no separate installation or implementation (assuming you have both Dynamics 365 Business Central and Dynamics 365 CRM already installed)
• Synchronized customer data for a seamless lead-to-cash process
• Price lists and item availability that automatically sync from Business Central to Dynamics 365 CRM
• More relationship management flexibility and customization possibilities than what is available in Business Central alone
Consider the following table to give you a general idea of which Dynamics 365 application might be a good fit for your company.

Difference between Dynamics 365 Sales Professional and Dynamics 365 Sales Enterprise are in the link below -
https://dynamics.microsoft.com/en-in/pricing/sales/#plans
Do let me know if this helped you.