The gemara has two opinions whether the time period that the nevi'im said prophesy about was referring to the days of Moshiach, indicating that there will be complete peace and significant differences between this world and the days of Moshiach, or whether they are saying their prophesy about olam ha'ba which comes after the days of Moshiach. Shmuel assumes the latter approach and therefore says that there will be no difference between the world we live in now and the days of Moshiach except for not being in servitude to the goyim. According to Shmuel, even in the days of Moshiach there will be both poor people and rich people and there will also be a need for weapons
Rav Yaakov Emden asks that the need for weapons should be dependent on being subject to the goyim. Since in the days of Moshiach we won't be under the control of the goyim, why would we require weapons? He answers that since it will be a time period where the victory of Yaakov over Eisav is very fresh, we will still require weapons to represent the victory and remind Eisav that we entered the realm of ורב יעבוד צעיר. The Ya'avetz understands that the days of Olam Ha'ba will be an entirely different reality where we won't even need to represent ourselves as being in control, but in the days of Moshiach we will still need to use the "props" to remind Eisav that we are in control.
Tosafos comments on the statement of Shmuel that there will also be another significant difference between nowadays and the days of Moshiach aside from the שעבוד גליות. In the days of Moshiach we will have Yerushalayim restored and a Beis HaMikdash. Why does Shmuel not mention this? Tosafos answers that the אין בין is not literal because there will be other differences. Rav Yaakov Emden (ya'avetz) adds that the focus of Shmuel is just on the nature of the world. The world will run in the days of Moshiach its natural course as it does nowadays. This seems to be Tosafos intent as well that אין בין is literal, but it doesn't refer to everything, it just refers to the world running naturally.
Rav Moshe (Heara 26) makes a very strong point. He doesn't understand why Tosafos is even bothered by the question of why Shmuel doesn't mention Yerushalayim and the Beis HaMikdash. The rebuilding of Yerushalayim and the Beis HaMikdash is not a mitzva that is going to be reintroduced in the days of Moshiach. It is a mitzvah today as much as it will be then, just that we are prevented from doing so due to the שעבוד גליות. We may also be missing education in terms of how to build it since we are missing nevuah. But these things are all part of the definition of ימות המשיח when the goyim will no longer have control over us. We will be free to rebuild Yerushalayim and the Beis HaMikdash. The Rambam (Melachim 11:1) actually lists under the responsibilities of Moshiach to restore the malchus beis dovid, rebuild the Beis Hamikdash and gather the Jews from wherever they are dispersed. The Rambam includes all this under the heading of שעבוד גליות, therefore the אין בין is completely literal and accurate.