This is one species pair where females can be easier to distinguish than males: female House Finches have a much plainer face than female Purple Finches. For both sexes, House Finches are more slender and have a longer tail that normally lacks a notch at the end.
The notched tail is not a reliable field mark. Any bird can appear to have a notched tail if it loses a feather or its feathers are displaced. The main things to look for are the streaking on the underside and the color of those streaks, the curved culmens, and the color of the wingbars.
The key word in what you've quoted is "normally". House Finches do often have an evident notch in the tail – search eBird for House Finch photos and you'll find lots of obvious House Finches with notched tails.
All of the birds in your photos have deep red rather than rosy red feathers, and the extent of the red on the body and wings is limited; they also all show extensive streaking on the belly. All of these are features of House Finches, not Purple Finches. Though the face pattern of the one female at the feeder isn't visible, its back and wings are the sandy grey-brown of a House Finch, not the dark brown of a Purple Finch.