Terumah

There are several key differences described in the preparation of the building of the Mishkan versus that of the building of the Beis HaMikdash.

Donations to the Mishkan were given voluntarily - may'ais kol ish asher yidvenu libo tikchu es terumasi. Donations to the Beis HaMikdash were given as a tax - vaya'al hamelech Shlomo mas (tax) mikol Yisrael.

Donations to the Mishkan were of specific items - zahav vakesef u'n'choshes... Donations to the Beis HaMikdash were not of items but of time and human labor - va'yehi hamas shloshim elef ish.

Once the items were collected for the Mishkan, many participated in its building - vechol ish chacham lev...vechol ishah chachmas lev beyadeha tavu. Once the items were collected for the Beis HaMikdash they were given to Shlomo Hemelech and Shlomo assigned the builders - vehabayis asher banah hamelech Shlomo laHashem...habayis hazeh asher ATAH boneh.

Similarly, the prerequisite for getting the Shechinah to dwell in the Mishkan was simply to build it - v'asu li mikdash v'shachanti besocham. Once it is built, Hashem will dwell in it. However, in reference to the Beis Hamikdash the pasuk has more detailed requirements - im tailaich b'chukosai v'es mishpatai ta'aseh. We are required to observe Torah and mitzvos to assure the resting of the Shechinah in the Beis HaMikdash, as the next part of the pasuk states - v'shachanti besoch Bnei Yisrael.

The building of the Mishkan seemed to have greater commitment from all of Bnei Yisrael than did the building of the Beis HaMikdash. Items were donated voluntarily and kept coming until they were told dayam - it's enough. Many took part in the building of the Mishkan and in fashioning its parts.

In contrast, the building of the Beis HaMikdash was a tax upon the people. They didn't give of themselves willingly or constantly. They worked for the Beis HaMikdash one month and then returned home for two months. In addition, the actual building seemed to be done by Shlomo's appointed workers rather than the people.

The commitment and effort of Bnei Yisrael during the preparation and the actual building of the Mishkan was so strong that its mere completion triggered the acceptance of their work by Hashem. Therefore, upon its completion, the Shechinah dwelt within it without any other prerequisite. The commitment and effort by the people in the building of the Beis HaMikdash by comparison, was lacking. Therefore, after its completion, Bnei Yisrael still needed to show a greater sense of commitment to Hashem. Observing Torah and mitzvos was the obvious choice to achieve this goal.

Davar acher - another interpretation.

The Mishkan was built in the desert when every aspect of life for Bnei Yisrael seemed to be obtained through miracles. Bnei Yisrael hardly had to do anything in the desert and still they witnessed the splitting of the sea, the falling of the manna, the well of Miriam, their clothes growing with them, etc. Therefore, the Mishkan also did not require a great deal of effort on their part. Tremendous effort would have been a most difficult request. During this time of miracles and constant gilui shechinah merely building the Mishkan was sufficient for assuring that the Shechinah would rest within it.

In contrast, during the time of the Beis HaMikdash, Bnei Yisrael were already living in a world of reality; planting, sowing, reaping, building, etc. Shlomo Hamelech recognized this difference and acted accordingly. Shlomo explained that they needed to build a Beis HaMikdash, a place of worship, a place where the Shechinah will dwell as it were, a place of holiness where Bnei Yisrael can gather and beseech Hashem for their needs. Nonetheless, they also needed to provide for their families. Donating all their valuables or, for that matter, all their time to the building of the Beis HaMikdash would have a negative impact on Jewish families and family life. Therefore, Shlomo instituted a tax to assure that people would not over zealously donate to the Beis HaMikdash at the expense of their respective families. Instead, they would spend some time working on the Beis HaMikdash and the rest at home with their families. They would not get involved with the intricate details of the building: Shlomo would do that, so they could have quality time to spend with their families.

Ultimately, the lesson Shlomo hamelech was teaching was that even in the framework of reality and daily life, there is a need to focus on the holiness of the Beis HaMikdash. Nonetheless, the holiness of the Jewish family has great importance. The lesson is to drive the holiness of the Mikdash into our homes and to bring our families to the holiness of the Beis HaMikdash bimherah b'yameinu.