Difference between Drivers for Service Tag & Find Latest Updates

Also lets say that on service tag as it is 23 updates are coming up - and the last time I did it [ive only had the computer a year] I only did say the updates that were recommended on the support assist.  Would I hypothetically need to go back and do all these 23 updates if I never did it from that approach before.?

It also keeps saying I have a critical firmware update I need to download but I have no idea if I need to do that that is a new message and I am choosing not to do the Bios update so IM afraid now to do anything that sounds like it has to do with Bios.  

I can try to get some sort of update - but one problem with the support assist is that it is a program which itself needs updated & I have yet to have that program tell me that it needs updating --  once it goes out of being current, it will stop scanning and checking.  I really don't know how to get reliable updates.  I think I saw something that said subscribe so I will have to check that.  Im not even sure if I am getting reliable windows updates apart from the ones that force you to update.

My question though which still is troubling is that the Support Assist and the dellsupport website will still only tell me that I need a few updates.  For instance, all of a sudden my audio is distorted so I went and saw there is a audio update.  But that never came up on my support assist [as far as I noticed].  There are about 30 new drivers and then on the support only about 5 things are needing updates so that is where my confusion is.  I will do more research and I think it seems to make sense if service tag search comes up with 23 and I can remember when the computer was purchased .  It wont show drivers that I already downloaded last time;  I don't think.  So, for instance if I last did it in April 2019 say would I go ahead and update everything since then?

@col25  finding drivers by Service Tag allows you to simply enter your Service Tag and (supposedly) see a list of only the drivers that apply to your specific system configuration, as opposed to all drivers for that system model, which might include hardware that isn't present on your configuration.  However, that system doesn't seem to be perfect.  I've seen it include drivers for hardware that isn't on the system in question and omit drivers that ARE applicable, so I always just search by system model.  I'd rather have to sift through some drivers that I know aren't relevant than miss drivers that are.

The "find updates" option relies on you having allowed an application to be installed on your system that will allow your hardware to be scanned so that the list of available drivers is based on the results of that scan.  I can't speak to how well that compares to the Service Tag method since I tend to prefer avoiding extraneous utilities on my system and I've been perfectly happy to search the entire list for my system model.  But I suppose if you had swapped some components within your system since you received it, the results from the scan might be different from a list based on Service Tag, even if the Service Tag list would have been perfect for your system's factory configuration (which it won't necessarily be).

In terms of which ones you need, if you just look at the list, you'd have to compare the available version to the version of the software you're already running, which can be tedious -- unless you happen to remember the last date you checked for drivers and are sure you brought your system completely current as of that date, in which case you can just look through what's been posted since then.  But that's still admittedly rather inconvenient.  I do it because I work in IT, so I'm used to downloading driver packages to facilitate system deployments and such anyway.  But the fact that that is NOT a typical user scenario is why applications like Dell SupportAssist and Dell Update exist, either of which are supposed to deliver essentially a Windows Update sort of experience for drivers and firmware.  If you have either of those installed, I'd just use them.  I believe that both of them set up a persistent system tray icon that changes its appearance when updates are available, which might help with remembering updates.  I'm not 100% sure of that, but if forgetting about updates is a concern for you and you haven't already done this, make sure that you configure Windows to always show that application's system tray icon in the actual system tray rather than hiding it in the "expansion drawer" that you access by clicking the little carat icon to the left of the icons actually shown in the tray.  If I'm right about the system tray icon looking different when updates are available, that might make that more noticeable to you.