If you match fixtures, those rooms will feel more connected and unified.

Some people, however, prefer the kitchen and living room to feel like separate spaces, so picking different (but not clashing!) fixtures will increase the feeling of changing rooms.

Match what you want to feel similar, change looks when you want to differentiate the spaces.

Keep in mind that your current architecture might already be leaning a certain way. Different ceiling hights, walls, half-walls, soffits, peninsulas, etc. will break up spaces and make it harder to unite different areas. Matching light fixtures, similar wall colors, and unified decorative elements help if you are wanting to overcome this.

Hope that helps!

Thanks! I think I need to unify- so you're advice is realy helpful.