IELTS UKVI stands for UK Visa and Immigration is designed for those who are willing to apply for UK only.
It has three categories including IELTS Academic, General and Life Skills.
Life Skills IELTS is the easiest one, Candidate just need to undergo 2 of the modules rather than four and it doesn’t have typical IELTS Pattern to follow, you may find yourself having a general conversation with the examiner and they will access to your ability of speaking and listening.
If you are applying for UK spouse visa then you have to do UK LIFE SKILLS which is consist of 2 modules Speaking and listening only.