Both are flagship Salesforce products built on the same platform but optimised for different workflows.
Sales Cloud — automates the sales process. Core objects: Lead, Opportunity, Account, Contact. Features: pipeline management, forecasting, sales paths, opportunity teams, quotes, products, price books, Sales Engagement (cadences). Used by Sales Reps, Sales Managers, RevOps.
Service Cloud — automates customer support. Core objects: Case, Account, Contact, Knowledge Article, Entitlement. Features: case routing (assignment + escalation rules), Service Console, Omni-Channel (skill-based routing), knowledge base, Field Service, Live Agent / Chat, social customer service. Used by Support Agents, Service Managers, Field Technicians.
Overlap: both run on the same Salesforce org; many customers use both. Account and Contact are shared. A single user can have access to both clouds.
Other clouds:
- Marketing Cloud (separate platform; integrates) — outbound marketing, journeys.
- Commerce Cloud — B2C and B2B e-commerce.
- Field Service — extension of Service Cloud for on-site work.
- CPQ / Revenue Cloud — extension of Sales Cloud for complex quoting and billing.
- Industries Clouds — Financial Services, Health, Manufacturing, etc. Pre-built data models for verticals.
A consultant's specialisation usually maps to one or two clouds (Sales + CPQ, or Service + Field).