The difference is monumental. One relies on creating a huge, disproportionate, non-transparent transfer of power over the population to various (unelected) actors. Power which they wield over the many.
One relies on creating a huge stockpile of data, which we have no reason to believe will be secure, will not be abused now or in the future, or accessed via the proper protocols for the proper reasons.
One relies on making service providers extensions of law enforcement and government over the populace.
One measure affects the degree to which people will be able to freely express themselves without worrying about how it might affect their future, or the future of the people they love.
One measure relies on digital footprints made in the past which can't be verified for actual human intent and authenticity, yet can lead to situations where, say, a hacker starts incriminating another person intentionally or unintentionally by creating digital footprints leading to them.
Both measures rely heavily on digital footprints that can't be questioned or verified or even proved to be accurate or even reliably called into questioned by a person under investigation. In some cases it won't even be clear that the digital footprints were used. At least with real time targeted surveillance the use of the data is more likely to be used to identify real threats and used to correlate digital prints with actual crimes, rather than what would occur with the blanket storage of information on the populace.
One measure weakens our ability as a society to function as a healthy democracy.
One measure is vastly more susceptible to abuse, misdirection, confabulation and mistaken identity.
One measure assumes we can trust government and law enforcement and service providers to do the right thing, all the time. Even when there is little evidence for that, just assess how many bankers and politicians are in jail for crimes committed. Unhealthy concentrations of power don't serve the good of the population.
One measure makes it even easier for bad actors to acquire data and thus power over not just ordinary citizens but our elected officials and people with positions of great responsibility. This can be used to compromise many aspects of government and business and probably already does.
At least with realtime targeted surveillance, the measure can be executed upon reasonable conditions. There are no reasonable conditions under which we can justify the blanket surveillance and data storage detailing the mental life of millions of people.
At least with realtime targeted surveillance, an individuals breach of privacy is complete, with its effects fairly understood. The damages of which are at least confined to a narrow range of people.
With the mass storage/mass surveillance practices the natural inclination will be to expand over time. One years storage will turn into 5 years, and 5 years will turn into decades. It will be incredibly cheap. More people will gain access, more use cases will be used for it. We have decades of evidence that this is how powers are expanded beyond the scope of their original intent. The damage that does will far exceed its benefits, for which we don't even have evidence today.
One measure is inherently coming from complacent motivations. Much more can be done to create more secure infrastructure. Much can be done politically to limit the proliferation of extremist violence and so on. Much more can be done, and isn't done, to persecute criminals with means we already have, but we don't. Yet certain parties are chomping at the bit to spend millions on these particularly gross measures under the myth that it's needed to do a better job.