Software development life cycle is a waterfall methodology,
it is a small to medium database software projects are 
generally broken down into six stages,project planning, 
requirements definition, design development, integration 
test, installation acceptance.....

SDLC is a methology in which covers all aspects of 
operations
It consists of 
Requirements Management.
System Analysis.
Design 
Coding
Testing
Support and Maintenance.
Post Audit.

SDLC is a complete proccess of analysis which includes 
feasiblity study,designing which includes conceptual 
desining&logical designing,coding,testing,implementation 
and then maintainaince.

SDLC for any project will have five phase
Initiation
Planning
Execution
Monitoring and control
Closing

Each phase will have various steps like project initiation
will start from project charter that is original 
confirmation of starting of the project and comes 
preparation of preliminary project scope statement, Scope 
planning, scope identification, creating wbs and wbs 
dictionary, scope verfication, scope control, time like 
duration and schedule of activities, estimation of project 
activities, definition of quality of project, defining 
communication ways and methods, acquiring resources, 
project integraton etc.,
these are general project managment process.
In case SDLC type of Water fall method, XP  and agile 
methodology, phase of project management project may vary 
for industry to industry like construction company will 
have different phase with that of manufacturing.
Project life cycle will be same for all project management 
life cycle or SDLC