I found that on Mate 19.10 we have lightdm and lightdm-settings packages installed, and also the ui of managing lightdm has changed, but when searching apt I found there is also lightdm-gtk-greeter, lightdm-gtk-greeter-settings and lightdm-autologin-greeter, are these packages different than the one installed on 19.10 ?
LightDM is a free and open-source X display manager that aims to be lightweight, fast, extensible and multi-desktop. It can use various front-ends to draw User Interface, also called Greeters .
LightDM GTK+ Greeter is a highly configurable login screen reminiscent of the classic GDM configuration.
LightDM GTK+ Greeter Settings is a small GUI written in Python which lets you modify various LightDM GTK+ Greeter settings, such as the theme, font, background, window position and more, settings which otherwise can only be set by modifying the greeter configuration files.
The greeter used since around Ubuntu MATE 17.10 is Slick Greeter, which is a fork of Ubuntu's Unity Greeter (16.04.2) maintained by the Linux Mint team to work on any distribution.