A Homeline is a standard POTS (Plain Old Telephone Service), copper-wired connection. VOIP phone, on the other hand, uses your Internet connection to make phone calls, rather than the standard phone wiring.
That means that VOIP, unlike a standard Homeline, is solely reliant on your Internet connection. The VOIP service requires an ATA supported router to work.
Please note a Homeline can only be used for the ADSL and VDSL plans, UFB is not compatible with a Homeline. The VOIP service, however, works for ADSL, VDSL and UFB.
The VOIP service can also be used on your mobile phone through 3rd party applications such as Zoiper.