We've stayed at both (several Timber Lodge stays, one Grand Residence stay). Both are very nice properties. As I understand things (and I'm sure someone will correct me if I'm wrong), MVC built Timber Lodge and it was sold as timeshare weeks. But they purchased Grand Residence from a prior owner that got into financial trouble. Grand Residence was sold as fractionals.
Noise is a big issue for us because my wife is a light sleeper. Grand Residence has a large number of different room configurations, and we did feel that our 1BR at Grand Residence was quite large and comfortable. But the reason we haven't returned to Grand Residence is that many of the rooms (including the one we were assigned) are close to the shops and restaurants. This meant that it can be noisy at night. Perhaps this would be less of a problem in the year of the Covid (remember that you're staying on the California side of the state line, and I simply don't know if restaurants and bars are open or not), but it was a problem for my sweetheart.
At Timber Lodge we usually request an high floor (not the top floor) room facing the interior courtyard. Even though there's a pool, and pools can be noisy, we find that this is much quieter for us.
Someone should pipe in and comment about parking. As MVC owners, we don't pay for parking at Timber Lodge (other than a tip for the valet). But if I remember, Grand Residence may charge a parking fee?