All 4 images here were shot within minutes of each other. The look is very different between the 2 sets of photographs.
The first 2 were shot using a solid ND filter, light tint towards blue.
The second set used a filter, a standard #4, however it was a graduated filter. The top part of the filter being darker to soften the bright sky and prevent over exposure.
I have several other filter types but I find most changes too drastic. These seem to work fine during a bright day (especially around water).