In this article, we are going to discuss the difference between HLD and LLD; and see the difference between them.
What is HLD?
High-Level Design in short HLD is the general system design means it refers to the overall system design. It describes the overall description/architecture of the application. It includes the description of system architecture, database design, brief description on systems, services, platforms and relationship among modules. It is also known as macro level/system design. It is created by solution architect. It converts the Business/client requirement into High-Level Solution. It is created first, before Low Level Design.
The solution architect develops the High-level design, which is used to specify the complete description or architecture of the application.
The HLD involves system architecture, database design, a brief description of systems, services, platforms, and relationships among modules.
The HLD is also known as macro-level or system design. It changes the business or client requirement into a High-Level Solution.
What is LLD?
Low Level Design in short LLD is like detailing HLD. It refers to component-level design process. It describes a detailed description of each and every module means it includes actual logic for every system component and it goes deep into each module’s specification. It is also known as micro level/detailed design. It is created by designers and developers. It converts the High-Level Solution into detailed solution. It is created as a second means after High-Level Design.
The LLD stands for Low-Level Design, in which the designer will focus on the components like a User interface (UI).
The Low-level design is created by the developer manager and designers.
It is also known as micro-level or detailed design. The LLD can change the High-Level Solution into a detailed solution.
The Low-level design specifies the detailed description of all modules, which implies that the LLD involves all the system component’s actual logic. It goes deep into each module’s specification.
HLD vs LLD
In the below table, we have discussed some significant comparisons between high-level design and low-level design.
| S.NO. | Comparison Basis | HLD | LLD |
|---|---|---|---|
| 1. | Abbreviation | It stands for High-Level Design. | It stands for Low-Level Design. |
| 2. | Definition | It is the general system design, which means it signifies the overall system design. | It is like describing high-level design, which means it signifies the procedure of the component-level design. |
| 3. | Purpose | States the concise functionality of each component. | States the particular efficient logic of the component. |
| 4. | Alternative Name | Also called a System or macro-level design. | Also called details or micro-level design. |
| 5. | Developed by | Solution Architect prepares the HLD. | Designer and developer prepare the LLD. |
| 6. | Sequential order in the design phase | It is developed first in sequential order. | It was developed after HLD. |
| 7. | Target Audience | It is used by management, program, and solution teams. | It is used by designers, operation teams, and implementers. |
| 8. | Conversion | Changes the client or business requirement into a high-level solution. | Changes the high-level solution to a comprehensive solution. |
| 9. | Probable output | The high-level design is necessary to understand the flow across several system objects. | A low-level design is required for creating the configurations and troubleshooting inputs. |
| 10. | Input Criteria | The input measure in HLD is SRS (Software Requirement Specification). | The input measure in LLD is the reviewed HLD |
| 11. | Output Criteria | The output measures in the HLD are functional design, database design, and review record. | The output bases in the LLD are the unit test plan and program specification. |
Conclusion
We can conclude that the high-level design specifies the complete report and planning of the particular software product or application. On the other hand, the low-level design specifies the in-detail report of all the modules.
Finally, we can say that both HLD & LLD are essential parts of the design phase in the SDLC process for any software product.
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